View, Critique, and Give Advice Pertaining to My Thesis Work

SYNTHESIS AND CHARACTERIZATION OF CONJUGATED MATERIALS WITH PHOSPHORUS

By FENG LI LAUGHLIN

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy

Thesis Advisor: Dr. John D. Protasiewicz

Department of Chemistry CASE WESTERN RESERVE UNIVERSITY

January, 2013

CASE WESTERN RESERVE UNIVERSITY

SCHOOL OF GRADUATE STUDIES

We hereby approve the thesis/dissertation of

Feng Li Laughlin ______

Doctor of Philosophy candidate for the ______degree *.

Thomas G. Gray (signed)______(chair of the committee)

Malcolm E. Kenney ______

Gregory P. Tochtrop ______

Lei Zhu ______

John D. Protasiewicz ______

______

(date) ______August 2012

*We also certify that written approval has been obtained for any proprietary material contained therein.

Dedicated To:

My family: Yingjie (mom), Patrick (husband), and Veronika

(daughter)

Table of Contents

Dedication……………………………………………………………………………………i

Table of Contents……………………………………………………………………………ii

List of Tables…………………………………………………………………………………iv

List of Figures………………………………………………………………………………vi

List of Schemes………………………………………………………………………………x

List of Abbreviations………………………………………………………………………xi

Acknowledgements…………………………………………………………………………xiv

Abstract……………………………………………………………………………………xvi

Chapter 1. General Introduction

1.1 π-Conjugated Materials ………………………………………………………………1

1.2 Conjugated Materials with Main Group Elements……………………………………3

1.3 Conjugated Materials with Phosphorus…………………………………………………7

1.4 Linear conjugated monomers and polymers with P=C Bonds………………………16

1.5 Benzoxaphospholes (BOPs)…………………………………………………………23

1.6 Proposed Work………………………………………………………………………25

1.7 Works Cited……………………………………………………………………………27

Chapter 2. Synthesis and Characterization of Benzobisoxaphospholes (BBOPs)

2.1 Introduction……………………………………………………………………………33

2.2 Results and Discussion………………………………………………………………42

2.3 Conclusions……………………………………………………………………………55

2.4 Experimental…………………………………………………………………………56

2.5 Works Cited…… ……………………………………………………………………63

Chapter 3. Synthesis and Characterization of Naphthoxaphospholes (NOPs)

3.1 Introduction …………………………………………………………………………65

3.2 Results and Discussion ………………………………………………………………68

3.3 Conclusions …………………………………………………………………………86

3.4 Experimental …………………………………………………………………………88

3.5 Works Cited …………………………………………………………………………104

Chapter 4. Synthesis and Characterization of Naphthobisoxaphospholes (NBOPs)

4.1 Introduction ……………………………………………………………………106

4.2 Results and Discussion …………………………………………………………115

4.3 Conclusions ……………………………………………………………………134

4.4 Experimental ……………………………………………………………………136

4.5 Works Cited……………………………………………………………………146

Chapter 5. Conclusions…………………………………………………………………150

Appendix A. Crystal Structure Determination and Data……………………………………155

Appendix B. Selected 31P{1H}, 1H and 13C{1H} NMR Spectra …………………………217

Appendix C. Absorption and Emission Spectra ……………………………………………296

Bibliography………………………………………………………………………………319

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List of Tables

Table 1.1 Absorption data for conjugated oligomers and polymer with P=P bond

-6 Table 2.1 Absorption and emission data for 2.19 (conc. 5 × 10 M in CH2Cl2, except 2.19d,

in MeOH)

-6 Table 2.2 Absorption and emission data for 2.20 (conc. 5 × 10 M in CH2Cl2)

Table 2.3 31P{1H} NMR data of BBOPs and BOPs

Table 2.4 13C{1H} NMR data of BBOPs and BOPs

Table 2.5 Selected Bond lengths (Å) and bond angles (˚) for 2.28a and 2.9

-6 Table 2.6 Absorption and emission data for 2.28 (conc. 5 × 10 M in CH2Cl2)

Table 2.7 Absorption and emission data for BOPs (MeOH)

Table 2.8 Reduction potentials for 2.28 (V vs. SCE)

Table 2.9 Reduction potentials for BOPs (V vs. SCE)

Table 2.10 Reduction potentials for 2.20 (V vs. SCE)

Table 2.11 Crystal data and collection parameters for 2.28a

Table 3.1 31P{1H} NMR data for BOPs and NOPs

Table 3.2 13C{1H} NMR data for BOPs and NOPs

Table 3.3 Selected bond lengths (Å) and bond angles (˚) for 3.3b and 3.3d

-6 Table 3.4 Absorption and emission data for NOPs (conc. 5 × 10 M in CH2Cl2)

Table 3.5 Reduction potentials for 3.3a-d and 3.3g (V vs. SCE)

Table 3.6 Crystal data and collection parameters for 3.12, 3.3b and 3.3d

31 1 Table 4.1 P{ H} NMR (CDCl3) data of R-NOPs and R2-NBOPs

Table 4.2 31P{1H} NMR data of BOPs and BBOPs

13 1 Table 4.3 C{ H} NMR (CDCl3) data for C=P atoms of R2-NBOP compared to R-NOPs

Table 4.4 Selected bond lengths (Å) and bond angles (˚) for compounds 4.5a and 4.5c

Table 4.5 P=C bond lengths (Å) for some other oxaphosphole compounds

Table 4.6 UV-vis and fluorescence of NOPs

Table 4.7 UV-vis absorption λmax

Table 4.8 Fluorescence emission data (nm) of NOPs and NBOPs

Table 4.9 Reduction potentials

Table 4.10 Crystal data and collection parameters of 4.4, 4.5a and 4.5c

List of Figures

Figure 1.1 The molecular orbitals of 1,3-butadiene

Figure 1.2 Examples of conjugated polymers

Figure 1.3 Examples of conjugated polymers containing heteroatom

Figure 1.4 Examples of multi-heterocyclic conjugated compounds

Figure 1.5 Examples of donor-acceptor-donor (DAD) conjugated materials

Figure 1.6 Compounds with Si=C bonds or Si=Si bonds

Figure 1.7 Comparison of frontier orbitals for some E=E bonds (E = C, N, P)

Figure 1.8 Structures of different types of conjugated moieties with phosphorus

Figure 1.9 Examples of conjugated materials with arylphosphane moieties

Figure 1.10 Conjugated materials containing phospholes

Figure 1.11 Examples of stable compounds with P=E bonds (E = C, Si, P)

Figure 1.12 Structures of building block: PPV vs. phospha-PPV

Figure 1.13 The first polymer with P=C bonds and the corresponding model compounds

Figure 1.14 Conjugated oligomers and polymers with P=P bonds

Figure 1.15 Examples of linear conjugated polymers with phosphorus

Figure 1.16 Structural diagram of 1.24a

Figure 1.17 Torsional angle of 1.24a

Figure 1.18 Structure of 2-substituted-1,3-benzoxaphospholes (R-BOPs)

Figure 1.19 Design of the new π-conjugated materials with OPs

Figure 1.20 Structure of target compounds BBOPs, NOPs and NBOPs

Figure 2.1 Different isomers of benzobisoxaphospholes (BBOPs)

Figure 2.2 Electronic delocalization

Figure 2.3 Compounds 2.9 with torsion angle

Figure 2.4 Compounds 2.10, Aryl-BBOPs

t Figure 2.5 Compounds Bu2-BBOP and Ad2-BBOP

Figure 2.6 Polymers with cis- and trans-p-benzobisoxazole building blocks

Figure 2.7 Monomers with cis- and trans-p-benzobisoxazole building block and polymer

Figure 2.8 Compounds 2.19 were prepared by Marlena P. Washington

Figure 2.9 Aryl substituted BBOP 2.20, prepared by Vittal B. Gudimetla1

1 Figure 2.10 H NMR spectrum of 2.28a (CDCl3, 400 Hz)

Figure 2.11 Compounds R2-BBOP with carbon position numbers

Figure 2.12 Thermal ellipsoid diagrams structural representation of 2.28a

Figure 2.13 UV-vis absorption spectrum and fluorescence emission of 2.28, emission excited

-6 at 300 nm (conc. 5 × 10 M in CH2Cl2)

Figure 2.14 Overlaid cyclic voltammograms for 2.28

Figure 2.15 Overlaid cyclic voltammograms for 2.20

Figure 3.1 Different isomers of naphthoxaphospholes (NOPs)

Figure 3.2 Thermal ellipsoid diagrams of 3.12

Figure 3.3 Packing diagrams of 3.12 showing intermolecular hydrogen bonding

Figure 3.4 Structure of 2-phosphino-naphthalene (3.14) and oxidized phosphine (3.13 )

Figure 3.5 MO diagram and SOMO for radical cation of 3.13

Figure 3.6 Thermal ellipsoid diagrams of 3.3b

Figure 3.7 Thermal ellipsoid diagrams of 3.3d

Figure 3.8 Packing diagram for compound 3.3d

Figure 3.9 Absorption and emission spectra of NOPs: 3.3a, 3.3b (top), 3.3c-g (bottom) (conc.

-6 5 × 10 M in CH2Cl2) vii

Figure 3.10 Compounds 3.3a-g (0.1 M in CH2Cl2) under room light and UV light

Figure 3.11 Cyclic voltammogram of 3.3a-d and 3.3g (conc. is 0.001 M in THF)

Figure 3.12 MO diagrams for Ph-NOP and Ph-BOP

Figure 3.13 MO diagrams for Ph-NOP and tBu-NOP

Figure 3.14 Scan rate vs. Ep plot of ferrocene redox couple

Figure 3.15 Scan rate vs. Ep plot of the redox couple of compound 3.3c

Figure 3.16 Variable scan rate voltammogram for compound 3.3c (scan rates of 25 to 200

mV/s, conc. is 0.001 M in THF)

Figure 4.1 Different isomers of naphthobisoxaphospholes (NBOPs)

Figure 4.2 Isomers of S-type of NBOP

Figure 4.3 Structure of S-type heterocyclic compounds

Figure 4.4 Naphthodithiophenes (NDTs) with S- and U-type structures

Figure 4.5 S-type of naphthodithiophenes (NDTs) 4.21 and 4.22

Figure 4.6 S-type of naphthodithiophenes (NDTs) 4.23

Figure 4.7 S-type naphthodifuran (NDF) 4.24

Figure 4.8 S-type naphthodifuran (NDF) 4.25

Figure 4.9 Dicyclopentanaphthalene (4.26), analogue of NDF

Figure 4.10 Naphtho[1,2-d:5,6-d’]bisoxazoles and Naphtho[2,1-d:6,5-d’]bisoxazoles

Figure 4.11 Structure of phosphate, phosphonate and primary phosphine

Figure 4.12 1H NMR spectrum of 4.5a

Figure 4.13 Structure of R2-NBOP with carbon position numbers

Figure 4.14 Structure and stability of 2.28a, 3.3a and 4.5a

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31 1 t Figure 4.15 Time-dependent P{ H} NMR spectra of Bu-BBOP (2.28a) in CDCl3 open to

air

31 1 t Figure 4.16 Time-dependent P{ H} NMR spectra of Bu-NOP (3.3a) in CDCl3 open to air

31 1 t Figure 4.17 Time-dependent P{ H} NMR spectra of Bu2-NBOP (4.5a) in CDCl3 open to air

Figure 4.18 Thermal ellipsoid diagram of 2,6-diphosphino-1,5-naphthylenediol (4.4)

Figure 4.19 Packing diagram for 4.4

Figure 4.20 Thermal ellipsoid diagram of 2,7-di-tert-butyl-naphtho[1,2-d:5,6-

d’]bisoxaphosphole (4.5a)

Figure 4.21 Thermal ellipsoid diagram of 2,7-di-phenyl-naphtho[1,2-d:5,6-

d’]bisoxaphosphole (4.5c)

Figure 4.22 Packing diagram for compound 4.5a

Figure 4.23 Packing diagram for compound 4.5c

Figure 4.24 UV-vis absorption spectra of R2-NBOPs (4.5a-c)

Figure 4.25 Solution of 4.16c (0.5 M in CH2Cl2) under room light and UV light (λF,max = 422

nm)

Figure 4.26 Fluorescence emission spectra of NBOPs (4.5a-c)

Figure 4.27 Overlaid cyclic voltammograms for 4.5a and 4.5c

Figure 4.28 Scan rate vs. Ep plot of ferrocene redox couple

Figure 4.29 Variable scan rate voltammogram for compound 4.5c

List of Schemes

Scheme 1.1 Synthesis of π-Conjugated oligomers with two P=C units

Scheme 1.2 Synthesis of π-Conjugated polymers with two P=C units

Scheme 1.3 Synthesis of 1.27 via phospha-Wittig strategy

Scheme 1.4 Becker reaction synthesis of 1.30

Scheme 1.5 Becker reaction synthesis of 1.32

Scheme 1.6 Becker reaction synthesis of 1.34

Scheme 1.7 Becker reaction synthesis of poly(p-phenylenephosphaalkene) 1.35

Scheme 1.8 Two synthesis routes to 2-R-1,3-benzoxaphospholes

Scheme 1.9 Mechanism of the cyclocondensation reaction produce R-BOPs

Scheme 2.1 Synthesis of 2-R-1,3-benzoxaphospholes (R = alkyl and aryl)

t Scheme 2.2 Synthesis of R2-BBOP (R= Bu and Ad)

Scheme 3.1 Synthesis routes for different NOP isomers

Scheme 3.2 Synthesis of 2-substituted-naphtho(2,3-d)oxaphosphole (2-R-NOPs)

Scheme 4.1 Synthesis routes for different NBOP isomers

Scheme 4.2 Synthesis of 2,7-di-R-naphtho[1,2-d:5,6-d’]bisoxaphosphole (R2-NBOP)

List of Abbreviations

R Alkyl

Ar Aryl

Me Methyl

Et Ethyl iPr iso-propyl tBu tert-Butyl

Ad Adamantyl

MeO Methoxy

Ph Phenyl

Mes 2,4,6-trimethylphenyl

Mes* 2,4,6-tri-t-butylphenyl

Dmp 2,6-dimesitylphenyl

Tip 2,4,6-triisopropylphenyl

PPV Poly(p-phenylenevinylene)

OP Oxaphosphole

BOP Benzoxaphosphole

BBOP Benzobisoxaphosphole

NOP Naphthoxaphosphole

NBOP Naphthobisoxaphosphole

PBO Poly(p-phenylenebenzobisoxazole)

PBOV Poly(benzobisoxazole-2,6-diylvinylene)

BBOZ Benzobisoxazole

NBOZ Naphthobisoxazole

NDT Naphthodithiophene

FVP Flash Vacuum Pyrolysis

NDF Naphthodifuran

DAD Donor-Acceptor-Donor

THF Tetrahydrofuran nBuLi n-Butyl Lithium

NEt3 Triethylamine

LDA Lithium diisopropylamide

n [ Bu4N][BF4] Tetrabutylammonium Tetrafluoroborate

Mp Melting Point

Calc. Calculated

NMR Nuclear Magnetic Resonance Spectroscopy

COSY Correlation Spectroscopy

HMBC Heteronuclear Multiple Bond Correlation

HMQC Heteronuclear Multiple Quantum Correlation

ORTEP Oak Ridge Thermal Ellipsoid Plot r. t. Room Temperature

EA Elemental analysis

HRMS High Resolution Mass Spectroscopy

UV-vis Ultraviolet-visible

CV Cyclic Voltammetry

SCE Saturated Calomel Electrode

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PL Photoluminescence

X-ray Single-crystal X-ray Diffraction Analysis

HOMO Highest Occupied Molecular Orbital

SOMO Singly Occupied Molecular Orbital

LUMO Lowest Unoccupied Molecular Orbital

Å Ångström mV Millivolts eV Electron-volt ns Nanosecond nm Nanometer h Hours

B3LYP Becke Three Parameter hybrid functionals and Lee, Yang, and, Parr

correlation functional

DFT Density Functional Theory

OLED Organic Light Emitting Diode

OFET Organic Field-effect Transistor

NLO Non-linear optical

xiii

Acknowledgements

I would like to thank my advisor, Dr. John D. Protasiewicz, for his greatest support, masterful guidance and inspiration during these years. I express my deepest gratitude to him, for all his wise advice and caring consideration, both within the chemistry discipline and my personal career.

I would like to thank my committee members, Dr. Thomas G. Gray, Dr. Malcolm E.

Kenney, Dr. Gregory P. Tochtrop, and Dr. Lei Zhu, for spending some of their valuable time to review, critique, and give advice pertaining to my thesis work.

I would like to thank all of my group members, both past and present, for their friendship, support, teaching and advice during these years. I would like especially acknowledge Dr. Vittal Babu Gudimetla, Dr. Marlena Washington, Dr. Andrew Shuffer,

Michael Rectenwald and Shanshan Wu.

I would like to thank Dr. Dale Ray for his assistance with NMR spectroscopy. I would like thank Dr. Thomas G. Gray and his group for the use of their UV-visible and fluorescence instrumentation. I thank Dr. Arnold L. Rheingold, James A. Golen (Depart. of Chem. and

Biochem., UCSD) and Nihal Deligonul for their assistance with X-ray crystallography. I thank Dr. Rhett C. Smith and Brynna J. Laughlin (Depart. Of Chem., Clemson U.) for assistance with lifetime measurements. I thank the University of Michigan Mass

Spectrometry facility for performing high-resolution mass spectroscopy measurements.

I would like to thank all the co-authors of my publication “Naphthoxaphospholes as examples of fluorescent phospha-acenes”, Arnold L. Rheingold, Nihal Deligonul, Brynna J.

Laughlin, Lee J. Higham and John D. Protasiewicz, for their important contribution.

xiv

I would like to thank all my family, teachers and friends, for their great support and help. Especially, I would like to thank my husband Patrick W. Laughlin. Without his support and help, I could not have achieved so much in both my research and life.

SYNTHESIS AND CHARACTERIZATION OF CONJUGATED MATERIALS WITH

PHOSPHORUS

Abstract

FENG LI LAUGHLIN

In this work, the synthesis and characterization of three series of conjugated compounds,

2,6-di-R-benzo[1,2-d:4,5-d’]bisoxaphospholes (R2-BBOPs), 2-R-naphtho(2,3- d)oxaphospholes (R-NOPs) and 2,7-di-R-naphtho[1,2-d:5,6-d’]bisoxaphospholes (R2-NBOPs) are reported. The investigation of BBOPs, NOPs and NBOPs extensively developed research of π-conjugated materials with P=C bonds.

xvi

These materials were fully characterized via: multi-nuclear magnetic resonance spectroscopy (NMR), melting points (MP), elemental analyses (EA) or high resolution mass spectroscopy (HRMS), ultraviolet-visible spectroscopy (UV-vis) and fluorescence spectroscopy. Some materials were characterized by cyclic voltammetry experiments (CV), and the solid state structures of selected materials were also determined by single-crystal X- ray diffraction analysis (X-ray). Density functional theory (DFT) calculations were employed as well. The comparisons of three series of compounds each other, as well as the relative compounds 2-R-benzo(1,3-d)oxaphospholes (R-BOPs) will also be discussed in this work.

Single-crystal structures of these conjugated materials, especially containing aryl substituents, display a coplanar configuration with almost 180˚ torsion angle.

Example: 2,7-di-phenyl-naphtho[1,2-d:5,6-d’]bisoxaphosphole (Ph2-NBOP, 4.5c)

The UV-vis absorption spectra of these conjugated compounds display absorption maxima peaks, featuring the π-π* transition between 304 nm to 387 nm, while the fluorescence emission spectra of these materials exhibit emission maxima peaks between 367 nm to 470 nm. Red shifts of both absorption and emission maxima were observed between

xvii alkyl and aryl substituted oxaphospholes (OPs). It demonstrates that aryl substituted compounds performed smaller HOMO/LUMO gaps than alkyl substituted counterparts.

Cyclic voltammetry experiments display initial reduction waves (Epc, V vs. SCE, conc. is 0.001 M in THF) at -1.90 (Ph2-NBOP), -1.92 (Ph-NOPs), -2.02 (Ph-BOPs), and -2.12

((2,4,6-Me3-C6H2)2-BBOPs), respectively. It reveals that initial reduction of Ph2-NBOP occurred more readily than counterparts of NOP, BBOP and BOP, which is attributed to its lower π* orbital.

xviii

Chapter 1: General Introduction

1.1 π-Conjugated Materials

π-Conjugated materials include small molecules (monomers), oligomers and polymers with π-conjugated systems, which are defined as spatially extended π-bonding systems.1

These systems fundamentally consist of alternating single and multiple bonds, in which the continuous overlap of p orbitals between the sp or sp2 carbon atoms results in delocalization of the electrons across the adjacent parallel aligned p orbitals.2 1,3-Butadiene, an example of a compound with conjugated double bonds, shows the overlap between the p orbitals of adjacent C=C bonds (Figure 1.1).

Figure 1.1 The molecular orbitals of 1,3-butadiene

Conjugated polymers did not attract considerable interest until the mid-1970s when a research team led by Alan G. MacDiarmid, Hideki Shirakawa and Alan J. Heeger discovered the conductivity of polyacetylene.3 The discovery and development of conjugated polymers by this team not only inspired both chemists and physicists to investigate π-conjugated materials, but also led to their receiving the 2000 Nobel Prize in Chemistry.4-6 Since 1978, many new conjugated polymers have been developed, including poly(p-phenylene), poly(p- phenylenevinylene) (PPV), and some aromatic heterocyclo polymers like polythiophene, polypyrrole, and polyaniline.7-12 Figure 1.2 shows some common conjugated polymers.13

Figure 1.2 Examples of conjugated polymers

Much effort has been devoted to the design and synthesis of a wide variety of conjugated polymers not only due to an interest in their properties, but also owing to potential industrial applications. Although early fundamental investigations had proclaimed conjugated materials as futuristic new materials that would lead to the next generation of electronic and optical devices,14 with the dramatic expansion of research, it is still surprising that conjugated

2 polymers have become the promised functionaled materials in view of the great potential for application in less expensive, easier fabrication, lightweight, and flexible electronic devices or photonic materials,15,16 such as organic/polymer light-emitting diodes (OLEDs/PLEDs),17-

19 field-effect transistors (FET),20-22 photovoltaic cells,23-25 non-linear optical (NLO) devices,26-28 photoresists,29 polymeric sensors,30 and some display devices such as electrochromic materials or smart windows.31

To achieve high performance in these applications, it is now necessary to explore novel polymers with π-conjugation. These new conjugated systems were expected to show high emission efficiency, fine-tunability of their band-gaps, processability, and dramatic improvements in durability, thermal-, air- and photo- stabilities, and other important characteristic properties. Therefore, much research has focused on tuning the structure and functional group of these conjugated materials with synthesis. For instance, controlling of the magnitude of π overlap along the backbone, grafting of bulky or functional side-chain substituent, or developing series of novel building blocks should efficiently modify and control their electronic nature such as band gap, HOMO and LUMO levels and effective conjugation length, etc.

1.2 Conjugated Materials with Main Group Elements

The design and synthesis of π-conjugated materials with main group elements (B, Si, N,

S, or P) to replace carbon in extending π-conjugated materials has rapidly become a vigorous research topic owing to their notable features such as effective orbital interactions, diversity in coordination numbers, and unique structural features around the main group element atoms.13,32,33 3

R R B N S n n n P1, Poly(p-phenyleneborane) P2, Polyaniline P3, Poly(p-phenylenesulfide)

N n S n Si n R P6, Polysilole (PSi) P4, Polypyrrole (PPy) P5, Polythiophene (PTh)

Figure 1.3 Examples of conjugated polymers containing heteroatom.

Some linear π-conjugated polymers (P1-P3) (Figure 1.3), which contain heteroatoms in their main chain, have been widely investigated. In them the heteroatoms participate in the π- conjugated systems by virtue of their available vacant orbitals (P1) or lone pairs (P2 and

P3).34-40 Among the heterocyclic π-conjugated polymers (P4- P6), polypyrrole (P4) and polythiophene (P5) (Figure 1.3) are the most widely studied heterocyclic pentadiene polymers. This is due to their high conductivity upon doping, their linear and nonlinear optical properties and their possible transparency in the visible region, all of which makes them attractive in the fabrication of devices.33 These materials are also very popular because of their high stability and their straightforward preparation via either electropolymerisation or metal-catalysed cross-coupling reactions,41-43 combined with the rich chemistry of the underlying monomers that allows for the preparation of numerous structural variants. In contrast, the preparation of silicon-contented polymeric materials has proved to be a significant challenge. Although some theoretical studies on polysilole (P6)44-46 have been performed in order to investigate the influence of the heteroatom on the band gap, there are

4 few conjugated polymers containing silicon have been published, including the first example of polysilole synthesized by West and co-workers in 1991.47

More recently, another significant type of conjugated material, called multi-heterocyclic conjugated material was developed. Although compounds C1 and C2 (Figure 1.4), which were synthesized by Murakami and co-workers,48 only contain an intramolecular B-N coordination bond, they exhibited interesting properties such as strong fluorescence.

Compound C3, which was reported by Grimsdale and co-workers,49 showed potential application as a new building unit for electronic devices due to its different optoelectronic properties.

Figure 1.4 Examples of multi-heterocyclic conjugated compounds

Figure 1.5 Examples of donor-acceptor-donor (DAD) conjugated materials

Compound D150 and D251 (Figure 1.4), which have also been described as donor- acceptor-donor (DAD) conjugated materials, were reported recently. By cross linking them, insoluble films of light-emitting and/ or charge-transporting polymer networks can be obtained. These DAD conjugated polymers with the charge-transporting units could be used to fabricate solution-processable electrochromic devices and organic field-effect transistors.

A crucial challenge of introducing the heteroatom E (E = B, Si, N, S, P et. al) in the conjugated system is implanting E into E=C bonds or an E=E bonds along the conjugated system. For instance, since the first stable disilene (1.1) (Figure1.6) was isolated by West and co-worker in 1881,52 there has been only a few investigations of conjugated materials with Si alone the conjugated system. Compound 2-silaallenes (1.2),53 which behaved as a highly reactive intermediate, could be trapped by suitable reagents and participated in reactions as precursor. The first tetrasilabutadiene (1.3) was synthesized in 1997 by Weidenbruch and co- workers.54 Research showed that this silabutadiene was thermally stable below 237 ˚C though it was extremely sensitive in the air.

Figure 1.6 Compounds with Si=C bonds or Si=Si bonds

1.3 Conjugated Materials with Phosphorus

In contrast to N or Si, phosphorus is considered as a good candidate as E to be employed in π-conjugated materials to replace C to form P=C or P=P bonds. This is due to the similarity in the electronegativity between phosphorus (2.2) and carbon (2.5) as compared to other main group elements such as nitrogen (3.1) or silicon (1.7). As a result, doubly bonded carbon compounds are more similar to doubly bonded phosphorus compounds than to silicon ones.55 Although P=C π bonds are weaker than C=C π bonds (180 vs. 272 KJ·mol-1),56

UV photoelectron spectroscopy and computational studies57 suggest that ethylene and phosphaethylene (HP=CH2) have similar frontier molecular orbitals. Figure 1.7 shows the comparison of frontier orbitals for some E=E bonds (E = C, N, P): P=C and C=C both have similar π-orbital energy, whereas P=C with the phosphorus lone pair n orbital being slightly lower. Additionally, for the π* bond, phosphaethylene (HP=CH2) has a much lower energy than ethylene, which is an important factor to decrease the band gaps. Nevertheless, the

HOMOs of N=N, N=C and P=P are the heteroatom long pair orbitals (n orbitals), which are different from P=C or C=C (π orbital). Based upon the fact that phosphorus and carbon exhibit very similar electron acceptor and electron donor abilities, allowing phosphorus compounds to be utilized instead of carbon species, the low-coordinate phosphorus was called the designation: “Phosphorus-the Carbon Copy”.55

Figure 1.7 Comparison of frontier orbitals for some E=E bonds (E = C, N, P). Reprinted with

permission from Washington, M. P.; Gudimetla, V. B.; Laughlin, F. L.; Deligonul, N.; He, S.;

Payton, J. L.; Simpson, M. C.; Protasiewicz, J. D. J. Am. Chem. Soc. 2010, 132, 4566.

Figure 1.8 Structures of different types of conjugated moieties with phosphorus

Figure 1.8 shows structures of different types of conjugated moieties with phosphorus, which have all been synthesized or been subjected to computational studies. While 1.4

(arylphosphane) and 1.5 (phosphole) contain phosphorus along the main chain, the phosphorus centers are involved in n-pπ conjugation (lone pair orbital on phosphorus).

Figure 1.9 Examples of conjugated materials with arylphosphane moieties

The first poly(para-phenylenephosphane)s 1.10a-c (Figure 1.9) with a well-defined structure were prepared by Lucht and co-worker in 2000.58 The UV-vis spectra of polymers

1.10a-c showed one absorption attributed to π-π* transitions with values of λmax ranging from

276 to 291 nm. The λmax of 1.10b (291nm) suggested the presence of some extended π electronic delocalization involving the phosphorus lone pair in poly(para- phenylenephosphane)s. However, polymers 1.10a-c possess rather high band gap values, which is probably due to the pyramidal geometry of the phosphorus atoms that prevents efficient conjugation of the phosphorus lone pair with the aryl groups.

The first phosphorus heterocycle oligomer that contained phospholes (1.11) was prepared and structurally characterized by Mathey and co-workers in 1994 (Figure 1.10),59 but the conjugation was disrupted by a lauge torsion angle (in the solid state, 25.1 - 49.7 ˚).

Later, when Mao and Tilley published the air-sensitive, soluble and yellow color phosphole- containing polymer (1.12, a and b) (Figure 1.10) in 1997,60 the UV-vis spectrum showed

10 maximum absorption at 308 nm, which was consistent with a relatively high optical band gap, should attribute to a preponderance of cross-conjugated segments.60 Since 2000, Réau and co- workers have prepared a series of oligomers containing phospholes (1.13, a-c) (Figure

1.10).61-63 It is noteworthy that the X-ray diffraction study performed on model compound

1.13a showed that the three heterocycles were almost coplanar (twist angle is 16.7 ˚), with the phosphorus atom being strongly pyramidalised. The solid state data also suggested a delocalization of the π-system over the thienyl substituents and the endocyclic π-system of the phosphole ring. The value of λmax recorded for 1.13a (412 nm) and 1.13b (490 nm) were considerably more red-shifted than those of related terthiophene (355 nm).63,64

Figure 1.10 Conjugated materials containing phospholes

Compound phosphorine (1.6, phosphorus analog pyridine, which is also called phosphabenzene)65-68 and Phosphinoylnitrene (1.9)69,70 have only had minimal theoretical study. In contrast, phosphaalkene (1.7) and diphosphene (1.8) have gained the most interest among these conjugated materials with phosphorus (Figure 1.11).

Figure 1.11 Examples of stable compounds with P = E bonds (E = C, Si, P)

Research on stable compounds containing P=E bonds (E = C, Si, P) did not experience a boom until the late 1970s when the first series of stable phosphaalkenes (1.14) were established by Becher (Figure 1.11).71 Following this, the first diphosphene (1.15) was prepared by Yoshifuji and co-workers in 1981,72 and the first phosphasilaalkene (1.16) was reported by Bichelhaupt and co-workers in 1984.73 However, compounds containing unsaturated multiple bonds between heavy elements are often unstable and favor formation of oligomers due to thermodynamic preference for two σ-bonds rather than one σ- and one π- bond. Since the isolation of those compounds was hampered by the low stability of the P=E bond, it has become necessary to incorporate some aromatic aryl group as the steric demanding substituents, to inhibit oligomerization of the double bond compounds. For instance, “Mes” and “Mes*” are every useful sterical protection substituents.

P P n n P n PPV phospha-PPV

Figure 1.12 Structures of building block: PPV vs. phospha-PPV

Figure 1.13 the First polymer with P=C bonds and the corresponding model compounds

The first π-conjugated polymer (1.19) (Figure 1.13) containing phosphaalkene subunits was an important milestone of development conjugated materials with phosphorus, which was synthesized by Gates and co-workers in 2002.74 Polymer 1.19, which was also called

(phospha-PPV) due to its analogue poly(p-phenylenevinylene) (PPV) (Figure 1.12), was prepared via [1,3]-silatropic rearrangement of an acylphosphane to a phosphaalkene by

71 methods used to prepare 1.14. The molecular weight of this polymer is rather modest (Mn =

2900-10 500 g/mol). And the product was obtained as a mixture of Z and E isomers and it was soluble in polar organic solvents. The UV-vis spectroscopy revealed a broad absorbance

(λmax = 328-338 nm), which confirmed a red shift with an increased degree of π-conjugation upon chain lengthening (corresponding model compound 1.17: λmax = 310 nm; 1.18: λmax =

314 nm).74 Although polymer 1.19 is the PPV analogue, the red shift was less pronounced than the one observed for native PPV (λmax = 120-130 nm), which would be attributed to conformational non-planarity in the main chain.

During the same period, two relevant diphosphene molecules (1.20a and 1.20b) bearing novel ligands were reported by Yoshifuji and co-workers75,76 and another family of conjugated polymers and oligomers with P=P bonds was considerably broadened by

Protasiewicz and co-workers (Figure 1.14). In 1996, Urnezius and Protasiewicz published diphosphene compound (1.21a).77 The new sterical protection substituent, 2,6- dimesitylphenyl (Dmp), was proved to be a very good aryl substituent to protect phosphorus oligomerization. In 2000, Shah and Protasiewicz synthesized stable red-orange color bis(diphosphene) (1.21b) bearing the same aryl sterically demanding groups.78 In 2004,

Smith and Protasiewicz reported two compounds (1.21c and 1.21d),79 which are comparable to 1.21a and 1.21b.

The studies of the variation of absorbance values along this series of monomers demonstrated that the P=P bond supports electronic communication across extended π- conjugated systems. Additionally, with the conjugation length increasing, the HOMO-LUMO band gaps were decreased, though, the HOMO-(HOMO-1) gap was observed in exact opposite.79 The same year, Smith and Protasiewicz also published conjugated polymer with

P=P bonds (1.22),80 which was the first conjugated polymer incorporating P=P linkages along the polymer backbone. The UV-vis spectroscopy revealed that, along with the increasing of the oligomers conjugation length (1.21, a to d) there was a consistent red shift on absorbance

(λn-π*), consequently illustrating an increase in the degree of conjugation, even if the red shift between oligomer and polymer (1.21c vs. 1.22) was slight (λn-π* = 9 nm) (Table 1.1). This was even less than the red shift between oligomer 1.18 and the phospha-PPV 1.19 (14~24 nm). Additionally, polymer 1.22 does not exhibit appreciable photoluminescence.

Figure 1.14 Conjugated oligomers and polymers with P=P bonds

Table 1.1 Absorption data for conjugated oligomers and polymer with P=P bond

P=P λπ-π* (nm) P=P λn-π* (nm)

1.21a 372 456

1.21b 398 476

1.21c 407 470

1.21d 422 481

1.22 435 481

1.10b 1.10c

1.19 1.10a

1.12a 1.22 1.12b

Figure 1.15 Examples of linear conjugated polymers with phosphorus58,60,74,80

1.4 Linear conjugated materials with P=C Bonds

Compared to the conjugated polymers with P=P bonds, the ones containing P=C bonds are more attracted my interests due to the similar frontier molecular orbitals between P=C and C=C. While the Protasiewicz group synthesized a series of oligomers and polymers with incorporating P=P units along the polymer backbone, they also focused on one with P=C units. These new conjugated materials were obtained via a highly efficient synthetic strategy based upon intermediate “phospha-Wittig” reagents Ar-P=PMe3, which were obtained by a

81 reduction of either DmpPCl2 or Mes*PCl2 with Zn dust in the presence of excess PMe3. In

2000, Shah used the same method to synthesize compounds (1.24) by reacting a di-“phospha-

Wittig” reagent and aldehyde (Scheme 1.1).78 These oligomers with two P=C units were proved to give an active π-π* transition. In 2003, Smith reported a series of polymers based upon building block 1.24, but extended the methodology. He used the dialdehyde to replace

16 the aldehyde, reacted with the bulky bis(dichlorophosphane), and obtained the polymers

(1.25a-d) featuring different π-linkers (Scheme 1.2).82 Among those polymers, however, full characterization of 1.25a-c were thwarted by their very limited solubility in organic solvents, and only the orange powder 1.25d was soluble in hexanes. The average degree of polymerization was 6, corresponding to a material with an average of 12 P=C units per chain

-1 with a modest Mn estimated at 6500 g mol . Notably, a significant aspect of this phospha-

Wittig reaction was that only E-configuration products were produced, making this method ideal for the preparation of π-conjugated materials. The polymer 1.25d exhibited a broad absorption band at λmax = 445 nm that presumably arises from a π-π* transition. This absorption band represented a substantial red shift as compared to the first polymer containing P=C units (1.19) (λmax = 328-338 nm), and even a 19 nm red shift versus E-PPV

83 (λmax = 426 nm). This polymer was also fluorescent with a broad emission centered on 530 nm, but the fluorescence intensity was weak compared to those from corresponding all- carbon analogues.

Scheme 1.1 Synthesis of π-Conjugated oligomers with two P=C units

π-Linker a tBu tBu S b

Zn H H π-Linker c xs PMe3 Cl2P PCl2 + π-Linker Fe O O - ZnCl2 -O=PMe3 OC6H13 tBu tBu d

1.25 C6H13O

Scheme 1.2 Synthesis of π-Conjugated polymers with two P=C units

These photoluminescence data suggested that the P=C units were certainly involved in the π-conjugated system, though with limited effective conjugation path lengths, which should contribute to non-planarity caused by the presence of the bulky aryl units. This was supported by the X-ray diffraction analysis of compound 1.24a (Figure 1.16),78 showing a torsional angle of 71˚ for the P=C unit with the central ring and a torsional angles of 22˚ for the P=C unit with the outer benzaldehyde derived rings (Figure 1.17).

Figure 1.16 Structural diagram of 1.24a, taken from literature paper.78 Reprinted with

permission from Shah, S.; Concolino, T.; Rheingold, A. L.; Protasiewicz, J. D. Inorg. Chem.

Figure 1.17 Torsional angle of 1.24a

(Black, planar of two P=C moieties; red, planar of P-aryl; blue, planar of C-aryl)

In 2004, Smith published a series of polymers (1.27a-c), which were exclusively in the

E-conformation via the employed π-conjugated building block 1.26.80 Compared to compound 1.24a containing two P=C bonds, the steric protection allowed successful isolation of the diphospha-Wittig reagent 1.26. Via this phospha-Wittig strategy, polymers 1.27 were prepared in 76-85% isolated yields as soluble orange (1.27a,b) or violet (1.27c) materials

(Scheme 1.3). These polymers are unaffected by heating at 140˚C for 6 hours under an inert atmosphere. The conjugation length for polymers (1.27a-c) are fairly high, though with the modest molecular weight (Mn = 5000-7300), the polymers display 18-26 repeat P=C units.

π‐linker π‐linker

π‐linker

Scheme 1.3 Synthesis of 1.27 via phospha-Wittig strategy

Following the publication of the first π-conjugated polymer containing phosphaalkene subunits 1.19, the Gates group reported a related π-conjugated polymer (1.35) and some model compounds (1.30, 1.32 and 1.34) in 2006.84 The monomer 1.30 was prepared by utilizing the Becker reaction of a silylphosphine 1.28 and acid chloride 1.29 (Scheme 1.4).

Notably, only one Z-isomer of 1.30 was present selectively, which was confirmed by NMR spectrascopy (both 31P and 13C) and X-ray crystallography. Compounds 1.32 and 1.34 are both bis(phosphaalkene) containing two P=C moieties, and were prepared by the same

Becker reaction. Compound 1.32 was a “C-centered” compound, where carbon attached on the opposite position of one benzene ring. It was synthesized by two silylphosphine (1.28) and diacid chloride (1.31) (Scheme 1.5). In contrast, 1.34 was a “P-centered” compound, where phosphorus attached on opposite position of one benzene ring. It was synthesized by a new bifunctional hindered di(phosphine)arylene (1.33) and two equivalent acid chlorides

(1.29) (Scheme 1.6). Analogous to 1.30, 1.32 and 1.34 were both obtained by Z,Z-selective formation, which was confirmed by an X-ray crystal structure analysis.84 A corresponding polymer 1.35 was prepared by heating 1.33 and 1.31 to 85 ˚C for 2 hours (Scheme 1.7). This bright orange colored polymer was insoluble in common organic solvents and primarily of Z- configuration, which was proved by 13C{1H} CP MAS solid-state NMR spectroscopy. Due to

20 an insoluble orange/brown solid that precipitated from the reaction mixture after several hours, the THF soluble portion of this precipitate of 1.35 was analyzed by UV-vis spectroscopy. Compared to the relative model compounds, 1.35 was observed a red shift in the absorbance maximum assigned to the π-π* band (1.35, 394 nm; 1.30, 324 nm; 1.32, 388 nm; 1.34, 337 nm). However, twist angles between the P=C plane and the unsubstituted arenes were 16˚-26˚, while those between the P=C plane and methyl-substituted arenes were even greater (59˚-67˚).

Scheme 1.4 Becker reaction synthesis of 1.30

Scheme 1.5 Becker reaction synthesis of 1.32

Scheme 1.6 Becker reaction synthesis of 1.34

Scheme 1.7 Becker reaction synthesis of poly(p-phenylenephosphaalkene) 1.35

Either the phospha-Wittig strategy or the Becker reaction, could successfully synthesize

“phospha-PPV” types of polymers with P=C bonds along the main chain (polymers 1.19,

1.25, 1.27 and 1.35). Those polymers featured smaller HOMO/LUMO gaps compared to native organic PPV; they had a modest degree of polymerization and some of them were soluble in common organic solvents. However, these linear polymers exhibited limited UV- vis absorption red shift compared with the oligomers, which illustrated the limited decreased energy on band gaps, thus a limited increase in conjugated ability along with the overlap of p orbitals. It was the mainly reason that interrupted the communication of π-conjugated bonds cross the whole conjugation system. Furthermore, in order to stabilize P=C bonds, it was necessary to possess sterical bulky groups as substituents demanding more difficult syntheses and higher molecular weights which did not contribute to the photonic properties in the polymer materials. Additionally, they exhibited limited photoluminescence due to the high energy of band gaps.

Therefore, considering the above disadvantages, some other conjugated materials containing the P=C moieties should be investigated. The idealized geometry for maximum conjugation for new conjugated materials with P=C moieties should have coplanar

22 conformations. It would also be ideal if they have good solubility, good stability and high photoluminescence.

1.5 Benzoxaphospholes (BOPs)

2-Substituted-1,3-benzoxaphospholes (R-BOPs) (Figure 1.18) are heterocyclic conjugated compounds, which are composed of a five membered ring containing oxygen and phosphorus (oxaphospholes, OPs) fused on a benzene ring. This type of rigid conformation enforces a coplanar structure, which should enhance π-conjugation. Furthermore, R-BOPs display far greater stability compared to their acyclic counterparts, while they do not require the extreme sterical substituents to protect the P=C moieties.85

Figure 1.18 Structure of 2-substituted-1,3-benzoxaphospholes (R-BOPs)

The first benzoapholspholes, 2-tBu-1,3-benzoxaphosphole (1.36a) was obtained by

Heinicke and Tzschach in 1980,85 other research concerning synthesis routes, mechanism, as well as physical and chemical properties followed in the next several years.86-88 Two synthesis routes to 1,3-benzoxaphosphole have been mentioned (Scheme 1.8): (1) products

1.36a-e were formed in the reaction of o-phosphinophenols (1.37) with N-arylimidoyl

23 chlorides RCCl=NAr; (2) The second route to 1,3-benzoxaphospholes 1.36a, b, f consisted of the cyclodehydration of o-H2PC6H4O2CR (R=Me, t-Bu, Et) 1.38 by P4O10.

Scheme 1.8 Two synthesis routes to 2-R-1,3-benzoxaphospholes

Beside the synthesis methods, the mechanism of the cyclecondensation reaction (1) was also investigated.88 Scheme 1.9 shows the proposed cyclocondensation mechanism:

Scheme 1.9 Mechanism of the cyclocondensation reaction produce R-BOPs

UV-vis spectroscopy revealed that with the aryl substituents (R = Ph, 4-ClC6H4, 4-

MeOC6H4), compounds 1.36c-e exhibited absorption attributed to π-π* transitions with values of λmax ranging from 329 to 364 nm, which illustrated that this type of coplanar small molecules have even smaller HOMO/LUMO gaps than the first phospha-PPV (1.35, λmax =

328-338 nm). It is also noteworthy that compounds with the aryl substituents were fluorescent in MeOH (1.36c, 416 nm, 1.36e, 416 nm).88

1.6 Proposed Work

For the reasons all above, new conjugated compounds with oxaphospholes (OPs) should be designed and synthesized. Figure 1.19 shows the structures of some possible OPs.

Figure 1.19 Design of the new π-conjugated materials with OPs

Considering the synthesis methods and the conjugation, three structures were selected and prepared, 2,6-di-R-benzo[1,2-d:4,5-d’]bisoxaphospholes (R2-BBOPs), 2-R-

2,3naphthoxaphospholes(R-NOPs) and 2,7-di-R-naphtho[1,2-d:5,6-d’]bisoxaphosphole (R2-

NBOPs) (Figure 1.20).

Figure 1.20 Structure of target compounds BBOPs, NOPs and NBOPs

In this work, the synthesis of 2,6-di-R-benzo[1,2-d:4,5-d’]bisoxaphospholes (R2-

BBOPs), 2-R-2,3naphthoxaphospholes(R-NOPs) and 2,7-di-R-naphtho[1,2-d:5,6- d’]bisoxaphosphole (R2-NBOPs) are reported, which would extensively developed the research of π-conjugated materials with P=C bonds. These compounds were characterized included multi-nuclear magnetic resonance spectroscopy (NMR), melting points (MP), elemental analyses (EA) or high resolution mass spectroscopy (HRMS X ), ultraviolet-visible spectroscopy (UV-vis), and fluorescence spectroscopy. Some of materials were characterized by cyclic voltammetry experiment (CV) and the solid state structures of selective materials were also determined by single-crystal X-ray diffraction analysis (X-ray). The density functional theory (DFT) calculations were employed as well. The comparisons of relative compounds R-BOPs, R-NOPs, R2-BBOPs and R2-NBOPs are also discussed in this work.

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(80) Smith, R. C.; Protasiewicz, J. D. J. Am. Chem. Soc. 2004, 126, 2268.

(81) Shah, S.; Protasiewicz, J. D. Chem. Commun. 1998, 1585.

(82) Smith, R. C.; Chen, X.; Protasiewicz, J. D. Inorg. Chem. 2003, 42, 5468.

(83) Simmons, W. W. The Stadtler Handbook of UltraViolet Spectra; Sadtler

Research Laboratories, Philadelphia, Pa., 1979.

(84) Wright, V. A.; Patrick, B. O.; Schneider, C.; Gates, D. P. J. Am. Chem. Soc. 2006,

128, 8836.

(85) Heinicke, J.; Tzschach, A. Z. Chem. 1980, 20, 342.

(86) Heinicke, J.; Tzschach, A. Z. Chem. 1983, 23, 439.

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(88) Heinicke, J.; Tzschach, A. Phosphorus Sulfur Relat. Elem. 1985, 25, 345.

Chapter 2: Synthesis and Characterization of Benzobisoxaphospholes (BBOPs)

2.1 Introduction

The experimental work presented in this chapter comprises the author’s contribution to published work.1

Benzobisoxaphospholes (BBOPs) are heterocyclic conjugated compounds which contain one benzene ring fused with two oxaphospholes (OPs) five membered rings. There are two possible isomeric structures, while the two OPs either fused on benzene next to each other (A and B) or in the opposite position (C and D) (Figure 2.1). There are other possible isomers for each of them, cis- (A and C) and trans- (B and D) configuration (nomenclature of

“cis” and “trans” is adopted by analogy to 2,6-disubstituted benzobisoxazoles2).

Figure 2.1 Different isomers of benzobisoxaphospholes (BBOPs)

Considering the electronic delocalization, only A and D afford conjugation across the whole heterocyclic ring structure as resonance structures shown in Figure 2.2. As the potential candidate of building block which would be polymerized to form rigid π-conjugated oligomers or polymers, D was selected as the first compound to synthesize and characterize.

Figure 2.2 Electronic delocalization

The investigation of BBOPs was planned as an extension from the study of benzoxaphosphole (BOPs). The first BOP, 2-tBu-1,3-benzoxaphosphole (2.8a) was obtained by Heinicke and Tzschach in 1980.3 After that pioneering work, a series of 2-R-1,3-

34 benzoxaphospholes (R = alkyl and aryl) were synthesized, and the continuous studies of synthetic routes, mechanism, as well as physical and chemical properties were investigated by the same group.4-7 The most effective method to synthesize R-BOPs (2.8) with various R group (R = alkyl and aryl) utilizes a cyclocondensition of o-phosphinophenols (2.4) with N- arylimidoyl chlorides (2.7) (Scheme 2.1). Primary phosphine compound 2.4 is an air sensitive colorless solid which can easily be prepared from commercially available materials. Phenol

(2.1) was phosphorylated by diethyl chlorophosphate to yield phosphate 2.2. Then a phospho-

Fries rearrangement, an efficient way to convert an aryl phosphate ester [Ar-OP(=O)(OR)2]

8,9 into an ortho-hydroxyaryl phosphonate [o-OH-Ar-P(=O)(OR)2], was employed to convert compound 2.2 to 2.3 by lithium diisopropylamide (LDA). A consequently reduction by lithium aluminum hydride (LiAlH4) was applied on 2.3 to produce the primary phosphine

(2.4) under nitrogen. On the other hand, various substituted acid chlorides (2.5) were reacted with aniline, and then followed by reaction with thionyl chloride to give the final product substituted imidoyl chlorides 2.7.

Compared to the synthetic routes of linear phosphaalkene compounds containing P=C bonds, for instance, 1.30 was prepared in 5 steps and the final step isolated yield was 40%,

BOPs had a simple synthetic route with modest yields (50-71%),6 which allowed modified methods to employ for synthesis of BBOPs.

Scheme 2.1 Synthesis of 2-R-1,3-benzoxaphospholes (R = alkyl and aryl)

Additionally, Hausen and Weckler reported the first X-ray crystal structure for BOPs,

10 2-p-chlorophenyl-1,3-benzoxaphosphole (2.9, 4-ClC6H4-BOP) (Figure 2.3). The X-ray data indicated that 2.9 exhibited coplanar conformation with the torsion angle (P=C-C=C) is

177.8˚ (Figure 2.3), and maintains the phosphorus carbon double bond in five membered cyclic ring. Therefore, a series of compounds containing two aryl substituents benzobisoxaphospholes (aryl-BBOP) (2.10) was designed and synthesized by Gudimetla

(Figure 2.4).11 The reactions were monitored by 31P{1H} NMR spectroscopy and the products formation were evident by their characteristic chemical shift near 80-90 ppm, however, the isolation of pure materials unfortunately became problematic, and various attempts for the isolation and purification of these materials was unsuccessful by aqueous methods.3,6,12

Figure 2.3 Compounds 2.9 with torsion angle

Figure 2.4 Compounds 2.10, Aryl-BBOPs

t Thus, two alkyl-substituted BBOPs, Bu2-BBOP and Ad2-BBOP were prepared (Figure

2.5). Both tert-butyl and adamantyl substituents are bulky groups which are often used to stabilize compounds. Nevertheless, the alkyl substituted BBOPs would be used as comparison compounds for the aryl substituted BBOPs.

t Figure 2.5 Compounds Bu2-BBOP and Ad2-BBOP

Since the early 1980s, rigid-rod polymers with 2,6-benzobisoxazole (BBOZ) units and various linkers in the main chain, poly(p-phenylenebenzobisoxazole) (PBO) (2.11-2.13)

(Figure 2.6), have been studied.13 Containing the π-conjugated systems, PBO brought many outstanding PL and NLO properties, as well as good mechanical properties and great thermal stability. Additionally, an analogue of PBO, poly(benzobisoxazole-2,6-diylvinylene) (PBOV)

(2.14) also has been synthesized and been proved that its UV and PL spectra were red shifted significantly compared to PBO due to the higher electronic delocalization.14,15

Figure 2.6 Polymers with cis- and trans-p-benzobisoxazole building blocks

Contrast in cis-2,6-di-R-benzobisoxazole units (2.11-2.14), trans-di-R- benzobisoxazoles building units and polymers were investigated as well. For instance, compound 2,6-dialkylbenzo[1,2-d;4,5-d’]bisoxazoles (R = Me, Et, Pr, H2NCH2, H2NCH2CH2) were reported by Osman in 1973,16 and the polymer (2.15) (Figure 2.6) were prepared by

Nozawa and co-workers in 1990.17

Although the monomers and polymers with BBOZ were studied several decades ago, many of them were not investigated as π-conjugated materials and utilized in photo- or electro- devices until 2008 due to solubility issues. Jeffries-EL and co-workers published a series of model compounds with both cis- (2.16) and trans- (2.17) BBOZ building units and one polymer (2.18) (Figure 2.7).2 These materials would use in organic semi-conducting applications since they combined efficient electron transport, photoluminescence, and nonlinear optical properties with excellent mechanical strength and thermal stability. Especially, the UV-vis and fluorescence spectroscopy of this novel polymer 2.18 exhibited the λmax at

476 nm and a green fluorescence with an emission maximum at 515 nm due to the electron- deficient BBOZ moiety.

Figure 2.7 Monomers with cis- and trans-p-benzobisoxazole building block and polymer

The investigations and achievements of BBOZs and BOPs inspired us to explore the new research area, benzobisoxaphospholes (BBOPs). In 2010, two series of compounds were

39 published.1 2.19a-j (Figure 2.8) were synthesized by Washington, and 2.20a-b (Figure 2.9) were synthesized by Gudimetla.

In this paper, the extended investigation of BOPs was reported, included the synthesis and photoluminescence (PL) properties, though the synthesis and some UV-vis absorption data of 2.19a-c already have been reported.6 The UV-vis absorption spectroscopy revealed that the λmax value of 2.19 were close, which between 337-351 nm (in CH2Cl2), except 2.19d, which showed at 281 nm (in MeOH) (Table 2.1).1 The outlying of absorption maximum of

2.19d could be explained by alkyl substituted derivative owing shorter conjugated length contrast in aryl substituted ones, which causes a greater value of HOMO/LUMO gaps. One might expected that the wavelength of fluorescence emission maximum of 2.19d are shorter than rest of 2.19 compounds, it showed at 426 nm for 2.19d while λF, max value of other compounds between 421-438 nm. The quantum yield showed significant difference between

2.19d and other derivatives. The aryl substituted BOPs featuring fair high quantum yield which between 0.55-0.69, over ten times greater than alkyl substituted BOP 2.19d (F =

0.04).

Figure 2.8 Compounds 2.19a-j were prepared by Washington1

-6 Table 2.1 Absorption and emission data for 2.19a-j (conc. 5.0 x10 M in CH2Cl2, except

2.19d, in MeOH)

R R’ λmax (nm) λF,max (nm) ΦF  (ns)

C6H5 H 337 425 0.57 12.0

4-ClC6H4 H 343 427 0.62 11.8

4-MeOC6H4 H 348 437 0.63 13.5

Ad H 281 426 0.04 9.0

4-BrC6H4 H 343 426 0.62 11.9

4-MeC6H4 H 343 426 0.69 7.0

i C6H5 Pr 339 421 0.55 5.8

i 4-ClC6H4 Pr 345 424 0.58 28.0

i 4-MeOC6H4 Pr 351 438 0.56 25.0

i 4-MeC6H4 Pr 342 429 0.56 4.8

Compounds 2.20a and b are the first published aryl substituted BBOPs (Figure 2.9).

These compounds were synthesized via same routes to BOPs, but used hydroquinone as the start material instead of phenol. The UV-vis absorption maxima of them were 337 and 336 nm (Table 2.2), respectively, while the emission maxima were 432 and 436 nm, respectively, used the same measuring conditions as 2.19. The PL data of BBOPs are similar to BOPs, however, there are striking differences in the quantum yield (2.20a, F = 0.27, 2.20b, F =

0.22). Noteworthy, both 2.19 and 2.20 displayed greater air and water stability than previously reported phospha-PPVs.

Figure 2.9 Aryl substituted BBOP (2.20a and b), prepared by Gudimetla1

-6 1 Table 2.2 Absorption and emission data for 2.20a and b (conc. 5.0 x10 M in CH2Cl2)

R λmax (nm) λF,ma x (nm) ΦF  (ns)

2,4,6-Me3C6H2 337 432 0.27 3.7

2,6-Me2C6H3 336 436 0.22 2.3

In this work, two alkyl-substituted BBOPs featuring two P=C bonds were synthesized and fully characterized.

2.2 Results and Discussion

2.2.1 Synthesis

Two target compounds, 2,6-di-R-benzo[1,2-d:4,5-d’]bisoxaphospholes (2.28a, R = tBu,

2.28b, R = Adamantyl (Ad)) were prepared via cyclocondensation, which coupling 2,5- diphosphinohydroquinone (2.24) with N-substituted-benzimidoyl chlorides RClC=NPh (R = tBu, Ad) (2.27) (Schem 2.2) via reflux in diethyl ether (Scheme 2.2).1

The synthetic routes to 2.24 were modified literature procedures9,18,19 that started from commercial available hydroquinone (2.21). The reaction of 2.21 with diethyl chlorophosphate using triethylamine (Et3N) as base in the tetrahydrofuran (THF) producted tetraethyl 1,4- phenylene bis(phosphate) (2.22). In this work, compare to reference procedures, THF was used for solvent instead of chloroform, and the ratio of 2.21 to diethyl chlorophosphate was 1:

2.2 instead of 1: 1.7 in literature.9 The workup procedure was modified by washing with acid and base, which HCl solution (1.2 M, 150 mL) and NaOH (1.0 M, 100mL) were added to extract the excess diethyl chlorophosphate. As a result, liquid product 2.22 was obtained in decent yield (92.1% vs. the literature yield 75%).

The reaction was followed by the anionic double phospho-Fries rearrangement to tetraethyl(2,5-dihydroxy-1,4-phenylene)bis(phosphonate) (2.23) using lithium diisopropylamide (LDA), which was generated in situ form diisopropylamide and n- butyllithium in THF.8 The ratio of 2.22 to LDA was 1: 2.2, which is different than reported in literature (1: 4.4), and the light yellow solid 2.23 was obtained in a 31.3% yield, which was lower than literature report (55.7%).9

Consequently, the primary diphosphine, 2,5-diphosphinohydroquinone (2.24) was obtained by reduction of 2.23 by lithium aluminum hydride (LiAlH4). It is worth to note that

43 the stability of compound 2.24 was good enough apply column chromatography as a purification procedure, or give specifics. The yield of this novel precursor 2.24 was 72.3% after chromatography.

Secondary phenyl amides (2.26a and b) and imidoyl chlorides (2.27a and b) are known compounds. The synthesis routes presented here were followed Ijzerman and coworkers.20

Commercially available substituted-acyl chloride (2.25a and b) was used as the starting material that was converted into secondary phenyl amides (2.26a and b) by reacting with aniline, when triethylamine (Et3N) was used as base in ethyl acetate. This was followed by the direct reaction of 2.26 with thionyl chloride (SOCl2). Various imidoyl chlorides 2.27 were synthesized in high yield (2.27a, 87.0%; 2.27b, 89.3%) (Scheme 2.2).

t Scheme 2.2 Synthesis of R2-BBOP (R= Bu and Ad)

2.2.2 NMR spectroscopic studies

The compounds R2-BBOP (2.28) were characterized by nuclear magnetic resonance

(NMR) spectroscopy, which include 31P{1H}, 1H and 13C{1H} NMR spectroscopy. The

31 1 P{ H} NMR spectroscopy in chloroform-d (CDCl3) data are compiled in Table 2.3. The chemical shift of compound 2.28a shows at 78.1 ppm while 2.28b at 76.7 ppm. Compared to

31 the large downfield P NMR spectroscopy chemical shift of phosphaalkene R1P=CR2R3

(200-300 ppm),21 compounds 2.28 presented a typical oxaphospholes chemical shift, which is consistent with BOP counterparts, and shows chemical shift between 75–95 ppm.1,6 However, the 1-2 ppm down field shifts of BBOPs versus to BOPs counterparts (Table 2.3) illustrate that, R substituted groups had minor impact on phosphorus ( = 0.9 - 1.4 ppm). The heterocyclic ring, in contrast, had bigger impact on the phosphorus ( = 1.2 - 1.7 ppm).

Table 2.3 31P{1H} NMR data of BBOPs and BOPs

R BBOP (ppm) BOP (ppm) heterocyclic ring impact  (ppm)

tBu 78.1 76.46 1.7

Ad 76.7 75.51 1.2

R impact  (ppm) 1.4 0.9

1 The H NMR (CDCl3) of 2.28 display two sets of resonences, one is corresponding the aromatic protons which is around 8.1 ppm, while another set of peaks between 1-3 ppm, which depended upon the R substituents. Figure 2.10 shows an example of the 1H NMR spectrum of 2.28a in CDCl3 (400 Hz).

1 Figure 2.10 H NMR spectrum of 2.28a (CDCl3, 400 Hz)

Table 2.4 13C{1H} NMR data of BBOPs and BOPs

BBOPs BOPs

C2 (C=P) (ppm) J value (Hz) C2 (C=P) (ppm) J value (Hz)

tBu 215.7 63.1 214.06 64.56

Ad 216.0 62.6 214.31 62.41

There are four peaks that observed on the 13C{1H} NMR spectrum if the chemical shift of carbons on R groups are ignored. Based on the reference compounds BOP,6 the chemical shift of carbon on C=P bond was around 216 ppm and shown a doublet due to coupling with the phosphorus atom (quantum spin number of P, % abundance = 100 %, I = ½). The coupling constant of C=P bond is about 63 Hz, which were also consistent with BOPs (Table

2.4). Beside the carbon on P=C bond (C2, Figure 2.11), rest of carbon were also assigned,

46 depending upon the coupling constant: C1 at 111 ppm (d, JPC = 22.1 Hz), C3 at 156 ppm (dd,

JPC = 11.3 Hz, 3.0 Hz) and C4 at 135 ppm (dd, JPC = 38.8 Hz, 2.1 Hz), respectively.

Figure 2.11 Compounds R2-BBOP with carbon position numbers

2.2.3 Single Crystal X-ray Diffraction Crystallography

X-ray quality crystals of 2.28a of were grown at room temperature in diethyl ether by slow evaporation, and the single-crystal structure of 2.28a is shown in Figure 2.12. The P=C bond length of 1.694(1) Å is somewhat longer than that found in most phosphaalkenes and shorter than the P-C(3) single-bond distance of 1.782(1) Å, but is consistent with such distances found in benzoxaphospholes (Table 2.5).10 The angle about the phosphorus atom is

88.34(5)˚.

Figure 2.12 Thermal Ellipsoid diagram of 2.28a

Table 2.5 Selected Bond lengths (Å) and bond angles (˚) for 2.28a and 2.9

2.28a 2.910

P=C 1.694(1) 1.712(7)

P-C 1.782(1) 1.788(4)

C-P-C 88.34(5) 88.1(1)

2.2.4 UV-vis and Fluorescence

The photoluminescence data for 2.28 are shown in Table 2.6, and the data for literature compounds BOPs with alkyl substituents are shown in Table 2.7. Compared to the BOP counterparts, 2.28a is red shifted in the absorption maximum assigned to the π-π* transition

(2.28a, 304 nm; tBu-BOP, 272 nm6), which can be explained as the conjugated length increased by an extra fused oxaphosphole ring. 2.28b exhibited a similar red shift in absorption maximum to counterpart of BOP (2.28b, 306 nm; Ad-BOP, 281 nm1), which is consistent with the 2.28a (Figure 2.13). However, compared to the aryl substituted BOPs,

2.19a-c and e-j, which λmax between 337 nm-351 nm (Table 2.1), and aryl substituted BBOPs,

2.20a and b (Table 2.2), which λmax between 336 nm-343 nm, 2.28 displayed a blue shift of absorption maxima.

Compared to tBu-BOP (2.8a) and Me-BOP (2.8b), which no fluorescence were observed,6 Table 2.6 shows fluorescent emission maxima of 2.28 at 372 and 367 nm, respectively. However, compared to the 2.19a-c and e-j, which λF,max between 421-438 nm

(Table 2.1), and 2.20a and b (Table 2.2), which λF,max between 432-436 nm, 2.28 displayed a

45-60 nm blue shift of emission maxima under the same conditions of measurement in same

48 solvent (Figure 2.13). Smaller stokes shift of alkyl-BBOPs (~60 nm) compared to aryl-BOP

(~80 nm) and aryl-BBOP (~100 nm) illustrated that minimal rearrangement of the molecules upon photoexcitation. The quantum yields of 2.28 are low (a, F = 0.04; b, F = 0.03), which is consistent to the Ad- BOP (2.19d, F = 0.04).

-6 Table 2.6 Absorption and emission data for 2.28 (conc. 5.0 x10 M in CH2Cl2)

-1 -1 R λmax (nm) ߝ, M cm λF, max (nm) Int. (a.u.) F  (ns)

tBu 304 12550 372 115 0.04 4.6

Ad 306 14600 367 130 0.03 3.9

Table 2.7 Absorption and emission data for BOPs (MeOH)1,6

R λmax (nm) λF, max (nm) F

Me 272, 222 -- --

tBu 272, 223 -- --

0.10 tBu -BBOP 2 0.09 Ad -BBOP 2

0.08

100 0.07

0.06

Abs. 0.05

50 0.04

0.03 (a.u.) Intensity Emission

0.02

0 300 400 500

Wavelength (nm)

Figure 2.13 UV-vis absorption spectrum and fluorescence emission of 2.28, emission excited

-6 at 300 nm (conc. 5.0 x10 M in CH2Cl2)

Fluorescence lifetime measurements were performed in anhydrous hexane to exploit the energy transfer and quenching at excited state. Compared to the fluorescence lifetimes of most aryl-BOPs which around 10-30 ns (Table 2.1), the lifetimes of 2.28 are shorter than most aryl-BOPs with 3.9 and 4.6 ns, for 2.28a and 2.28b respectively. Furthermore, aryl-

BBOPs (2.20) (Table 2.2) exhibited even shorter lifetime than 2.28 with 3.7 and 2.3 ns, for

2.20a and 2.20b respectively. It can be concluded that the BBOPs (2.28 and 2.20) featuring lower energy of singlet excited states (S1) than BOPs (2.19), which caused shorter fluorescence lifetime than 2.19.

2.2.5 Electrochemical studies of BBOP

Electrochemical experiments were performed on 2.28 to probe their reducibility in THF.

Cyclic voltammetry was used to measure the reduction under anhydrous conditions inside a nitrogen-filled drybox. Solution with a concentration of 0.001 M 2.28 in THF with a three- electrode system (glassy carbon as the working electrode, silver wire as the quasi-reference electrode, and platinum wire as the counter electrode) was utilized. All scans were performed

n with 0.1 M tetrabutylammonium tetrafluoroborate, [ Bu4N] [BF4], in THF as the supporting electrolyte, with a scan rate of 0.1 V/s. Ferrocene was utilized as an internal reference because of the use of a quasi-reference electrode during analyses. Ferrocene (final concentration 0.001 M) was added after the initial scans of compounds. The reduction potentials were thus referenced to the ferrocene/ferrocenium redox couple versus saturated calomel electrode (E1/2 = 0.55 V vs. SCE).

Table 2.8 Reduction potentials for 2.28 (V vs. SCE)

R Epc Epa E1/2

tBu -2.49 -2.20 -2.35

Ad -2.49 -2.22 -2.36

The cyclic voltammograms of 2.28 are shown in Figure 2.14, selected reduction potentials data (V vs. SCE) are displayed in Table 2.8. Compound 2.28a and b feature a single, reversible, one-electron reduction wave at E1/2 = -2.35 V vs. SCE, whereas the BOP counterpart has no reduction wave was observed, which was examined by CV under the same

51 conditions.22 The easier reduction process of BBOPs than BOPs could be explained by heterocyclic ring of BBOPs extended the species conjugation length than BOPs, and thus lower the π* orbital (reductive potential) (Table 2.8).

t Bu2‐BBOP

Ad2‐BBOP

Figure 2.14 Overlaid cyclic voltammograms for 2.28.22 Reprinted with permission

from Washington, M. P.; Gudimetla, V. B.; Laughlin, F. L.; Deligonul, N.; He, S.; Payton, J.

American Chemical Society.

However, compared to reduction potentials data of aryl-BOPs (2.19a-c and e-j) (Table

22 2.9), which have a reduction wave E1/2 between -1.90 to -2.11 V vs. SCE, the reduction of

2.28 occurs harder by about 300 mV. This result suggests that the π* orbital of 2.28 is much higher in energy than 2.19.

Figure 2.15 Overlaid cyclic voltammograms for 2.20.22 Reprinted with permission from

Washington, M. P.; Gudimetla, V. B.; Laughlin, F. L.; Deligonul, N.; He, S.; Payton, J. L.;

American Chemical Society.

It is notable that aryl substituted BBOPs, 2.20a and b display two, one-electron reduction waves (Figure 2.15), in which the first wave occurs near E1/2 = -1.98 V vs. SCE and

22 a second wave near Epc = -2.44 V vs. SCE (Table 2.10). The two reduction waves of aryl-

BBOPs, demonstrate that two P=C units are firmly locked into conjugation with one another.

Table 2.9 Reduction potentials for BOPs22 (V vs. SCE)

R R’ Epc Epa E1/2

2.19a C6H5 H -2.02 -1.77 -1.90

2.19b 4-ClC6H4 H -1.91 -- --

2.19c 4-MeOC6H4 H -2.16 -1.90 -2.03

2.19e 4-BrC6H4 H -1.81 -- --

2.19f 4-MeC6H4 H -2.08 -1.84 -1.96

i 2.19g C6H5 Pr -2.06 -1.80 -1.93

i 2.19h 4-ClC6H4 Pr -1.97 -- --

i 2.19i 4-MeOC6H4 Pr -2.25 -1.96 -2.11

i 2.19j 4-MeC6H4 Pr -2.16 -1.87 -2.02

Table 2.10 Reduction potentials for 2.2022 (V vs. SCE)

R Epc Epa E1/2 Epc

2.20a 2,4,6-Me C H 3 6 2 -2.12 -1.89 -2.01 -2.48 2.20b 2,6-Me C H 2 6 3 -2.07 -1.82 -1.95 -2.41

2.3 Conclusions

In conclusion, two new conjugated compounds incorporating P=C bond along the conjugated backbone (BBOPs) have been synthesized and characterized by NMR, UV-vis, fluorescence and CV, and one of them has been crystallographically characterized.

t The single-crystal structure of Bu2-BBOP (2.28a) shows a coplanar structure, which ideally maximize the conjugation across the whole conjugated back bone. The P=C bond length of 1.694(1) Å is longer than that found in most phosphaalkenes (~1.67 Å) and shorter than the P-C single bond (~1.78 Å). R2-BBOPs exhibited better photoluminescence than R-

BOPs, which absorption maxima around 305 nm and emission maxima around 370 nm. It is attributed to the extension of BBOP’s conjugated length by fused two oxaphospholes, which decreased the HOMO/LUMO gaps and consequently increased the conjugation compare to the BOPs. The quantum yields of R2-BBOPs was low (a, F = 0.04; b, F = 0.03), due to the alkyl substituents, which as same as the alkyl substituted Ad-BOP (F = 0.04).

Cyclic voltammetry experiments revealed that 2.28a and b feature a single, reversible, one-electron reduction wave near E1/2 = -2.35 V vs. SCE, whereas the BOP counterpart has no reduction wave was observed. It should explained by heterocyclic ring of BBOPs increased the species conjugation, and lower the π* orbital (reductive potential), consequently easier the reduction process of BBOPs.

Since these materials possess significant photoluminescent and electrochemical properties, BBOPs have the potential to exploite as active layers in organic-based electrooptic devices such as OLEDs.

2.4 Experimental

General Procedures:

Reactions were conducted under nitrogen using either Schlenk line techniques or within an MBraun drybox. Tetrahydrofuran, toluene and diethyl ether were dried by distillation from sodium and benzophenone ketyl. Hexanes was dried by distillation from sodium benzophenone in the presence of tetraethylene glycol dimethyl ether. Methylene chloride was dried by distillation from calcium hydride. Methylene chloride (99.8%, for spectroscopy) and ethanol (200 proof) were degassed prior to use for UV-vis and fluorescence spectroscopy. Benzimidoyl chlorides were prepared following literature protocols.20 NMR

1 31 1 spectra ( H and P{ H}) were recorded in CDCl3, unless otherwise noted, on a Varian

INOVA AS-400 spectrometer operating at 399.7 and 161.8 Hz, respectively, and 31P{1H}

13 1 NMR spectra were referenced to 85% H3PO4. C{ H} NMR spectra were recorded in CDCl3 on a Varian INOVA AS-600 spectrometer operating at 150.9 Hz, unless otherwise noted.

UV-vis and fluorescence spectra were recorded using a Cary-5G-UV-vis-NIR spectrophotometer and a Cary Eclipse spectrometer, respectively. Anthracene in ethanol was

-6 23 used as a standard for quantum yield measurements (CH2Cl2, conc. 5 × 10 M). The excitation slit width for all measurements was kept at default settings (5 nm). Melting points were examed on a Thomas Hoover Capillary Melting Point Apparatus. Elemental analyses were performed by Robertson Microlit Laboratories, Ledgewood, New Jersey. High resolution mass spectrometry was performed by the University of Michigan Mass

Spectrometry facility using a VG (Micromass) 70-250-S magnetic sector spectrometer with

EI technique at 70 eV.

Tetraethyl 1,4-pheylene bis(phosphate) (2.22)

Triethylamine (26.8 mL, 191 mmol) was added drop wise to a mixture containing hydroquinone (2.21) (10.0 g, 90.8 mmol) and diethyl chlorophosphate (29.0 mL, 200 mmol) in 100 mL THF in a 500 mL round bottom flask with a stir bar. The blue color solution was stirred for 18 h at room temperature. Aqueous HCl solution (1.2 M, 150 mL) was added, the mixture solution was stirred until precipitate disappeared, and CHCl3 200 mL was added to extract the product. The organic layer was separated and washed successively with aqueous

NaOH (1.0 M, 100 mL), distilled water and brine, and it was dried over anhydrous sodium sulfate. The solvent was removed by rotary evaporation to yield a brown liquid 2.22 (32.0 g,

1 31 1 92.1%); H NMR (CDCl3): δ 7.17 (s, 4H), 4.20 (m, 8H), 1.33 (m, 12H); P{ H} NMR

(CDCl3): δ -5.63.

Tetraethyl(2,5-dihydroxy-1,4-pheylene)bis(phosphonate) (2.23)

To a solution of diisopropylamide (5.8 mL, 41.3 mmol) in 100 mL THF at -78 ˚С in a nitrogen atmosphere in a 500 mL round bottom flask with a stir bar, nBuLi (2.5 M in hexane,

16.5 mL, 41.3 mmol) was added. The mixture was stirred for 30 min to allow white slurry lithium diisopropylamide (LDA) to form. Tetraethyl 1,4-phenylene phosphate (2.22, 4.00 g,

10.3 mmol) was dissolved in 100 mL THF in a 250 mL round bottom flask, and then transferred to LDA by cannula. The mixture solution was stirred at -78 ˚С for 1 h and then removed the dry ice/acetone bath, stirred additional 1 h at r. t. The mixture solution then poured over saturated ammonium chloride aqueous solution (100 mL), and then stirred until the precipitate was dissolved. The product was extract with 100 mL diethyl ether. The organic layer was separated, and the aqueous layer was extracted by 100 mL CH2Cl2. The combined organic layer then was washed by distilled water and brine, dried over anhydrous

57 sodium sulfate. The solvent was removed by rotary evaporation to yield a light yellow solid

1 2.23 (1.54 g, 39.1%) H NMR (CDCl3): δ 9.72 (s, 2H, OH) 6.99 (m, 2H), 4.12 (m, 8H), 1.34

31 1 (m, 12H); P{ H} NMR (CDCl3): δ 20.4.

2,5-diphosphinohydroquinone (2.24)

Tetraethyl(2,5-hydroxy-1,4-phenylene)bis(phosphonate) (2.23, 2.60 g, 6.80 mmol) was added a solution of LiAlH4 (1.94 g, 51.1 mmol) in THF 250 mL in a 500 mL round bottom flask with a stir bar. The solution was refluxed under nitrogen for 24 h, an aqueous solution of saturated ammonium chloride was added drop wise to quench the excess LiAlH4, and product was extracted with chloroform (150 mL). The organic layer was separated, and filtered through celite using glass fritted filter funnel. Solvents were removed by rotary evaporation to yield a crude product. Purification by column chromatography (diethyl

1 ether/hexanes 1:1, Rf = 0.8) led to isolation of a white solid 2.24 (0.855 g, 72.3%); H NMR

31 1 (CD3OD): δ 6.76 (m, 2H), 3.95 (s, 2H), 3.44 (s, 2H). P{ H} NMR (CD3OD): δ -143.9.

2,6-di-tert-butyl-benzo[1,2-d:4,5-d’]bisoxaphosphole (2.28a)

In a drybox, 2,5-diphosphinohydroquinone (2.3, 0.302 g, 1.78 mmol) was dissolved in

150 mL diethyl ether in a 250 mL round bottom flask with a stir bar, the flask was sealed and removed from the drybox. N-phenylpivalimidoyl chloride (0.767 g, 3.92 mmol) was added and the flask was outfitted with a reflux condenser and flushed with nitrogen, the solution was refluxed for 36 h. The reaction mixture was filtered using glass fritted filter funnel. The solid was extracted with diethyl ether (2 × 15 mL), the combined filtrate was evaporated under vacuum. The crude product was extracted in hexanes and filtered through basic alumina, the solvent was removed by rotary evaporation to yield white solid 2.4a (0.364 g,

1 3 4 68.9%); H NMR (CDCl3): δ 8.13 (d, 2H, JPH = 2.0 Hz), 1.47 (d, 18H, JHH = 1.2 Hz);

31 1 13 1 P{ H} NMR (CDCl3): δ 78.1 (s); C{ H} NMR (CDCl3) (100 Hz): δ 215.7 (d, JPC = 63.1

Hz), 156.8 (dd, JPC = 11.3 Hz, 3.0 Hz), 135.7 (dd, JPC = 38.8 Hz, 2.1 Hz), 111.5 (d, JPC =

-6 22.1 Hz), 38.3 (d, JPC = 11.9 Hz), 29.7 (d, JPC = 9.1 Hz); UV (CH2Cl2, conc. 5 × 10 M):

-1 -1 -6 λmax, nm (ߝ, M cm ) 304 (12550); fluorescence (CH2Cl2, conc. 5 × 10 M): λF,max, nm (Int.)

372 (115); quantum yield (CH2Cl2): ΦF 0.04; lifetime (CH2Cl2):  (ns) 4.6 ± 0.2; mp: 137-

140˚С; elemental analysis: calc. for C16H20O2P2 (M. W. 306.28), C 62.74%, H 6.585%; found:

C 63.02%, H 6.94%.

2,6-di-adamantyl-benzo[1,2-d:4,5-d’]bisoxaphosphole (2.28b)

In a drybox, 2,5-diphosphinohydroquinone (2.3, 0.389 g, 2.31 mmol) was dissolved in diethyl ether (approximately 200 mL) in a 250 mL round bottom flask with a stir bar, the flask was sealed and removed from the drybox. N-(adamantyl)benzimidoyl chloride (1.909 g,

6.94 mmol) was added, the flask was outfitted with a reflux condenser and flushed with nitrogen, and the solution was refluxed for 36 h. The reaction mixture was filtered using glass fritted filter funnel. The solid was extracted with diethyl ether (2 × 15 mL), the combined filtrate was evaporated under vacuum. The crude product was extracted in hexanes and filtered through basic alumina, the solvent was removed by rotary evaporation to yield a

1 3 white solid 2.4b (0.335 g, 31.3%); H NMR (CDCl3): δ 8.13 (d, 2H, JPH = 2.0 Hz), 2.13 (br s,

31 1 13 1 6H), 2.10 (s, 12H), 1.81 (s, 12H); P{ H} NMR (CDCl3): δ 76.7; C{ H} NMR (CDCl3)

(100 Hz): δ 216.0 (d, JPC = 62.6 Hz), 156.8 (dd, JPC = 10.3 Hz, 2.5 Hz), 135.6 (dd, JPC = 35.3

Hz, 2.6 Hz), 111.5 (d, JPC = 22.2 Hz), 41.9 (d, JPC = 9.3 Hz), 40.2 (d, JPC = 11.1 Hz), 36.6,

-6 -1 -1 28.3; UV (CH2Cl2, conc. 5 × 10 M): λmax, nm (ߝ, M cm ) 306 (14600); fluorescence

-6 (CH2Cl2, conc. 5 × 10 M): λF,max, nm (Int.) 367 (130); quantum yield (CH2Cl2): ΦF 0.03; lifetime (CH2Cl2):  (ns) 3.9 ± 0.6; mp: 324-327˚С; HRMS: 462.1890 (calc. 462.1878).

Cyclic Voltammetry of BBOPs

n Tetrabutylammonium tetrafluoroborate (Fluka), [ Bu4N][BF4], was recrystallized five times using ethyl acetate and ether, dried thoroughly under vacuum and stored in the drybox.

Ferrocene (Sigma-Aldrich) was purified via sublimation and stored in the drybox.

Tetrahydrofuran was dried by distillation from sodium and benzophenone. All glassware was cleaned and oven-dried overnight before use. Cyclic voltammetry experiments were performed in a nitrogen-filled Vacuum Atmospheres MBraun drybox outfitted with a CH

Instrument (CHI630C) Workstation at room temperature. A glassy carbon working electrode was polished with 0.05 micron alumina and thoroughly cleaned and dried before use. A silver wire was utilized as a quasi-reference electrode, and a platinum wire was the counter electrode. All scans were performed at a scan rate of 0.1 V/s with a potential window of approximately -3 to +1.5 V vs. saturated calomel electrode (SCE).

Fluorescence Lifetimes of BBOPs

Fluorescence lifetime measurements were performed under an atmosphere of dry nitrogen in a glove box. Approximately 2 mg of each sample was dissolved in 10 mL of anhydrous hexane to produce samples with optical densities of below 0.05. Each sample was subsequently filtered through a 0.2 μM PTFE syringe filter into a Spectrosil quartz cuvette having a path length of 1 cm. Each cuvette was sealed with a PTFE screw cap and the lifetimes were acquired. Lifetimes of sample solutions were measured using a PTI Easylife II

60 with an excitation wavelength of 340 nm. A 320 nm low band gap cut off filter was positioned between the sample and detector for these measurements to eliminate scattered excitation source light interference.

Crystallography

Summary of crystal data and collection parameters for crystal structure of 2.28a are provided in Table 2.11, and detailed descriptions of data collection as well as data solution are provided below. Compound 2.28a was done at Department of Chemistry, Case Western

Reserve University, Cleveland, OH 44106. Thermal ellipsoid projections were generated with

Mercury 2.3 software package (Figure 2.16). The crystal was transferred to a Bruker AXS

APEX II diffractometer with a CCD area detector, centered in the X-ray beam, and cooled to

100 K using a nitrogen-flow low-temperature apparatus that had been precisely calibrated by a thermocouple placed at the same position as the crystal. Compound 2.28a of X-ray quality crystals was grown at room temperature in diethyl ether by slow evaporation.

Table 2.11 Crystal data and collection parameters for 2.28a

t Bu2-BBOP

formula C16H20O2P2

fw 306.26

space group P2(1)/n

temperature (K) 100(2)

a (Å) 5.4948(5)

b (Å) 7.2202(7)

c (Å) 19.2488(18)

α (deg) 90.00

β (deg) 91.3450(10)

γ (deg) 90.00

V (Å3) 763.46(12)

Z 2

3 densitycalc (g/cm ) 1.332

radiation Mo Kα (λ = 0.71073 Å)

monochromator graphite

detector CCD area detector

no. of reflns measd hemisphere

2 θ range (deg) 6.02 – 55.7

cryst dimens (mm) 0.51 × 0.46 × 0.25

no. of reflns measd 8676

no. of unique reflns 7145

no. of observations 7145

no. of params 94

R, Rw, Rall 0.0291, 0.0864, 0.0298

GOF 1.132

2.5 Works Cited

(1) Washington, M. P.; Gudimetla, V. B.; Laughlin, F. L.; Deligonul, N.; He, S.;

Payton, J. L.; Simpson, M. C.; Protasiewicz, J. D. J. Am. Chem. Soc. 2010, 132, 4566.

(2) Mike, J. F.; Makowski, A. J.; Jeffries-El, M. Org. Lett. 2008, 10, 4915.

(3) Heinicke, J.; Tzschach, A. Z. Chem. 1980, 20, 342.

(4) Heinicke, J.; Tzschach, A. Z. Chem. 1983, 23, 439.

(5) Heinicke, J.; Tzschach, A. Phosphorus Sulfur 1984, 20, 347.

(6) Heinicke, J.; Tzschach, A. Phosphorus Sulfur Relat. Elem. 1985, 25, 345.

(7) Hsu, D.-T.; Lin, C.-H. J. Org. Chem. 2009, 74, 9180.

(8) Taylor, C. M.; Watson, A. J. Curr. Org. Chem. 2004, 8, 623.

(9) Dhawan, B.; Redmore, D. J. Org. Chem. 1984, 49, 4018.

(10) Hausen, H. D.; Weckler, G. Z. Anorg. Allg. Chem. 1985, 520, 107.

(11) Gudimetla, V. B. Conjugated low coordinate organophosphorus materials:

Synthesis, characterization and photochemical studies, Case Western Reserve University,

2010.

(12) Heinicke, J.; Gupta, N.; Surana, A.; Peulecke, N.; Witt, B.; Steinhauser, K.;

Bansal, R. K.; Jones, P. G. Tetrahedron 2001, 57, 9963.

(13) Wolfe, J. F.; Arnold, F. E. Macromolecules 1981, 14, 909.

(14) Wang, S.; Lei, H.; Guo, P.; Wu, P.; Han, Z. Eur. Polym. J. 2004, 40, 1163.

(15) Yakuphanoglu, F.; Okutan, M.; Zhuang, Q.; Han, Z. Physica B 2005, 365, 13.

(16) Osman, A. M.; Mohamed, S. A. Indian J. Chem. 1973, 11, 868.

(17) Nozawa, S.; Tayama, T.; Kimura, M.; Mukai, S. Int. Sampe Tech. Conf. 1990,

22, 680.

(18) Dhawan, B.; Redmore, D. J. Org. Chem. 1986, 51, 179.

(19) Nandi, M.; Jin, J.; RajanBabu, T. V. J. Am. Chem. Soc. 1999, 121, 9899.

(20) Van, d. N. A. M. C. H.; Pietra, D.; Heitman, L.; Goeblyoes, A.; Ijzerman, A. P.

J. Med. Chem. 2004, 47, 663.

(21) Quin, L. D.; Verkade, J. G. Phosphorus-31 NMR spectral properties in compound characterization and structural analysis; VCH, 1994.

(22) Washington, M. P.; Payton, J. L.; Simpson, M. C.; Protasiewicz, J. D.

Organometallics 2011, 30, 1975.

(23) Crosby, G. A.; Demas, J. N. J. Phys. Chem. 1971, 75, 991.

Chapter 3: Synthesis and Characterization of Naphthoxaphospholes (NOPs)

3.1 Introduction

The bulk of the work in this chapter comprises the content of a full paper

“Naphthoxaphospholes as examples of fluorescent phospha-acenes” in press.1

Naphthoxaphospholes (NOPs) are multi-heterocyclic conjugated compounds which

contain a naphthylene ring fused with an oxaphosphole (OP) five membered ring. There

are three possible isomers for the naphtoxaphospholes, 1α-NOP (3.1), 1β-NOP (3.2) and

2-NOP (3.3) (Figure 3.1).

Figure 3.1 Different isomers of naphthoxaphospholes (NOPs)

Based upon the synthetic routes to benzoxaphospholes (BOPs)2 and benzobisoxaphospholes (BBOPs),3 three NOP isomers could be prepared via the routes

showed on Scheme 3.1. Route (1) starts by phosphorylating 1-naphthol (3.4) with diethyl

chlorophosphate, followed by a phospho-Fries rearrangement, which transforms the

diethyl 1-naphthyl phosphate (3.5) to the single product diethyl(1-hydroxy-2-

naphthyl)phosphonate (3.6). In contrast, routes (2) and (3) start from phosphorylated 2-

naphthol (3.8) with diethyl chlorophosphate, followed by a phospho-Fries rearrangement,

which transformed the diethyl 2-naphthyl phosphate (3.9) to a mixture of products,

diethyl(2-hydroxy-1-naphthyl)phosphonate (3.10) and diethyl(3-hydroxy-2- naphthyl)phosphonate (3.12). According to the literature,4 3.10 and 3.12 yield in a ratio

of 1: 2 and only 3.12 was reported as a pure compound with a 39% yield. Consequently,

three primary phosphines, 2-phosphino-1-naphthol (3.7), 1-phosphino-2-naphthol (3.11)

and 3-phosphino-2-naphthol (3.13), might be obtained via reduction of these

phosphonates (3.6, 3.10 and 3.12) by lithium aluminum hydride (LiAlH4) under nitrogen.

Finally, NOPs with various R groups (R = alkyl and aryl) might be gained via

cyclocondensation of these possible primary phosphines (3.7, 3.11 and 3.13) with N- arylimidoyl chlorides.5

Considering the yield of 3.6 compared to 3.10 and 3.12, 3.1 was first chosen to

synthesize. However, after successfully prepared the compounds 3.5 and 3.6, the

synthesis route (1) was hampered by preparing 3.7, whose isolation and purification were a significant challenge.

Scheme 3.1 Synthesis routes for different NOP isomers

Compound 3.3 was chosen as a target compound for synthesis and investigation

due to the higher yield of compound 3.12 compared to 3.10. Additionally, it was a good candidate for polymerization and enhancement of th rigid nature desired of a π- conjugated polymer.

Furthermore, research of acenes and heteroacenes has also attracted much attention due to their photo and electrochemical properties. For heteroacenes, the heteroatom moieties increasing the stability of conjugated systems, featuring electrical and optical properties due to the nature of the heteroatomic moiety and deriving conjugated system by modification of the substituents.6-10 The advantages of heteroacenes, such as decent

solubility, smaller HOMO/LUMO gaps, semiconductivity and photoluminescence,

inspired design and synthesis of unique phospha-acenes.

The recently synthesized benzoxaphospholes (BOPs) and benzobisoxaphospholes

(BBOPs) could be good candidates for building block of π-conjugated polymers, due to

they not only featuring a coplanar structure, but also displaying significant

photoluminescence and electrochemical properties.3,11 In this work, we design, synthesize

and fully characterize 2-R-naphto(2,3-d)oxaphospholes (R-NOPs), which expended the

investigations of R-BOPs and R2-BBOPs. This study represents the first step towards the

creation of a series of increasingly extended electron deficient acene-like planar materials

featuring P=C bonds.

3.2 Results and Discussion

3.2.1 Synthesis of NOPs

The synthesis of diethyl(2-naphthyl)phosphate (3.9), diethyl(3-hydroxy-2-naphthyl)

phosphonate (3.12), 3-phosphino-2-naphthol (3.13) and 2-substituted-naphtho(2,3- d)oxaphosphole (2R-NOPs) (3.3) were modified methods of literature procedures,3,4,12

starting from commercially available materials. 2-Naphthol (3.8) was phosphorylated by

diethyl chlorophosphate, and produced a brown liquid 3.9 (95.9% of yield) (Scheme 3.2).

The phospho-Fries rearrangement13 was employed to convert 3.9 into 3.12, which was

purified by recrystallization in hexanes with a higher yield (51.4%) than the reported

literature.4

Phosphonate 3.12 was reduced using LiAlH4 to form a new primary phosphine 3.13.

This white solid displayed greater air stability than typical primary phosphines. For

example, solutions of 3.13 in CDCl3 solution at room temperature persisted for a month

or more without signs of decomposition (as ascertained by 1H and 31P{1H} NMR spectroscopy). In the solid state, 3.13 was stable for several months or longer.

Cyclocondensation of benzimidoyl chlorides with 3.13 in THF under nitrogen

t formed 3.3a-g (a, Bu-NOP, b, Ad-NOP, c, C6H5-NOP, d, MeC6H4-NOP, e, ClC6H4-NOP,

f, BrC6H4-NOP, g, MeOC6H4-NOP). Yields of 3.3a-g ranged from modest to good (28.8-

72.3%), owing to the difficulty in purifying the products from similarly soluble starting

materials and the anilinium salts. These new conjugated materials were isolated as

crystalline white (3.3a, b) or yellow (3.3c-g) solids that possessed reasonable air and

water stability, especially in the solid state. The stability in atmosphere of 3.13 and 3.3

greatly increased the possibility of synthesis and purification.

Scheme 3.2 Synthesis of 2-substituted-naphtho(2,3-d)oxaphosphole (2R-NOPs)

3.2.2 NMR spectroscopy studies

Both the heterocyclic ring and R group impact the 31P{1H} NMR spectroscopy

chemical shifts (Table 3.1), where the type of R group effect is quite large (6-14 ppm)

whereas the heterocyclic ring effect is only modest (2-3 ppm). The chemical shifts of

3.3a and 3.3b are between 72-74 ppm, while 3.3c-f has the range of 80-87 ppm. These

data consistently ca. 2-3 ppm upfield from similarly substituted R-BOPs.3 It was also

worth noting that the 3.3g, which features aryl substituent, however displays a chemical shift at 75.0 ppm. Compared with the BOPs analog, NOPs display a 2.5 ppm and 3.0 ppm upfield chemical shift for alkyl and aryl substituents compounds, respectively.

Table 3.1 31P{1H} NMR data for BOPs and NOPs

31P{1H}/ppm Substitution(R) BOP NOP /ppm

tBu 76.414 74.1 2.3

Ad 75.57 72.8 2.7

14 C6H5 86.3 83.7 2.6

7 4-MeC6H4 83.2 80.1 3.1

14 4-ClC6H4 88.5 85.8 2.7

7 4-BrC6H4 89.5 86.7 2.8

14 4-MeOC6H4 78.1 74.9 3.2

Table 3.2 13C{1H} NMR data for BOPs and NOPs

13 1 1 C{ H}/ppm ( JPC/Hz) Substitution(R) BOP NOP /ppm

tBu 214.0 (64.5)14 217.6 (63.6) 3.6

Ad 214.3 (62.4)7 217.9 (62.8) 3.6

14 C6H5 197.1 (55.3) 199.9 (55.3) 2.8

7 4-MeC6H4 197.4 (55.2) 200.3 (55.6) 2.9

4-ClC6H4 -- 198.3 (54.7) --

7 4-BrC6H4 195.3 (54.9) 198.3 (54.8) 3.0

4-MeOC6H4 -- 200.2 (55.6) --

In 13C{1H} NMR spectroscopy, the chemical shifts of carbon on the P=C bond for

NOPs are consistently 2.8-3.6 ppm upfield versus the counterparts of BOPs (Table 3.2).

1 The directly bonded coupling constants ( JPC) are both around 63 Hz for alkyl substituents, and around 55 Hz for aryl substituents R-NOPs. Based on Fermi-contact spin–spin coupling theory,15 the mechanism involves the electron density at the nucleus

(hence the s-orbital electron density), where an increase in the s character of the P-C bond is generally associated with an increase in the coupling constant. The 8 Hz coupling constants increasing for alkyl compared with aryl R group is attributed to enriching the electron density on the C by bonding alkyl R group, thus increasing the s character of the

P=C bond versus the aryl R group counterparts.

3.2.3 Single Crystal X-ray Diffraction Crystallography and Computational Studies

Figure 3.2 Thermal ellipsoid diagrams of 3.12. selected bond lengths (Å) and angles (˚):

P(1)-O(1), 1.4750(14); P(1)-O(2), 1.5641(15); P(1)-O(3), 1.5674(15); P(1)-C(1),

1.7835(17); C(1)-C(10), 1.426(3); C(10)-O(4), 1.354(2); O(1)-P(1)-O(2), 113.98(9);

O(1)-P(1)-O(3), 114.07(8); O(2)-P(1)-O(3), 102.14(8); O(1)-P(1)-C(1), 111.69(8); O(2)-

P(1)-C(1), 103.63(8); O(3)-P(1)-C(1), 110.49(8); C(12A)-C(11)-C(12), 25.8(4); C(11)-

O(2)-P(1), 118.91(16); C(13)-O(3)-P(1), 121.33(13).

Figure 3.3 Packing diagrams of 3.12 showing intermolecular hydrogen bonding

Single crystals of 3.12 suitable for an X-ray diffraction study were obtained from hexanes at -45˚C. The internal metrics for 3.12 were unexceptional, but the presence of intermolecular P=O•••HO hydrogen bonding leads to chains of molecules along the c- axis (Figure 3.3).

Compound 3.13 possessed greater air-stability than the 2-phosphino-naphthalene

(3.14) (Figure 3.4), which decomposes slowly in CDCl3 (72% of 2-phosphino- naphthalene remained after 7 days)16. An interesting predictive model for the enhanced stability of selected primary phosphines has recently been forwarded by Higham and

coworkers.16,17 Two electronic factors were found to be important. First, primary phosphines in which the presences of extended conjugation and/or heteroatoms were found to have HOMOs that was dislocated from the phosphino functionality, and enhanced air-stability. Second, the products of oxidation of the primary phosphines, radical cations, having SOMO energy levels above -10 eV will have enhanced air- stability. The oxidized phosphines, [RPH2] , are postulated to be involved in the air

oxidation of phosphines. We have thus undertaken analogous DFT calculations on 3.13 .

DFT studies on the radical cation of 2-phosphino-naphthalene (3.14) reveals a SOMO energy level of -10.64 eV, while similar calculations on the 3.13 shows a SOMO

energy level of -10.72 eV (see Supporting Information). One might initially predict less air-stability for compound 3.13 compared to 3.14, but as Figure 3.5 reveals, the SOMO of

3.13 has no significant phosphorus contributions. The special enhanced stability of 3.13

might thus be particularly attributed to shift in the SOMO away from phosphorus (unlike

2-phosphino-naphthalene). An interesting alternative explanation might lie in the nature

of the hydroxy substituent, for it has been shown that oxidation of secondary phosphines

can be inhibited by hydroquinones.18

Figure 3.4 Structure of 2-phosphino-naphthalene (3.14) and radical cation of 3.13

Figure 3.5 MO diagram and SOMO for radical cation of 3.13

X-ray diffraction-quality crystals of 3.3b and 3.3d were grown by slow evaporation at room temperature in diethyl ether and methylene chloride, respectively. The Thermal ellipsoid diagrams of 3.3b and 3.3d were depicted in Figure 3.6 and Figure 3.7, respectively. Summary of crystal data for 3.12, 3.3b and 3.3d is provided in Table 3.3.

For compound 3.3d, the crystal contains two crystallographic independent molecules. For the P-C single bonds, they are 1.806(3) and 1.789(3)/1.787(3) Å for 3.3b and 3.3d, responsively. The P=C double bonds for 3.3b and 3.3d are 1.700(3) and

1.716(3)/1.732(2) Å, respectively. Compound 3.3d has a longer bond length which

74 attributed to extend the conjugation of NOP by functionalization with aryl-substituent.

Consequently, there is more single-bond character located in the P=C bond, causing the longer bond length. Within the heterocyclic rings, 3.3b and 3.3d are both coplanar conformations with torsion angles of 178.06 and 171.23/179.32˚. The angles about the phosphorus atoms in 3.3b and 3.3d are very similar (88.0-88.3 ˚C).

Table 3.3 Selected Bond lengths (Å) and bond angles (˚) for compounds 3.3b and 3.3d

3.3b 3.3d

P=C 1.700(3) 1.716(3)/1.732(2)

P-C 1.806(3) 1.789(3)/1.787(3)

C-P-C 88.29(12) 87.97(13)/88.14(13)

Torsion angle 178.06 171.23/179.32

Figure 3.6 Thermal Ellipsoid diagram of 3.3b

Figure 3.7 Thermal ellipsoid diagrams of 3.3d

It is worth to note that the crystal packing of 3.3b is unexceptional, but the packing of molecules of 3.3d is more interesting in the crystal lattice as displayed in Figure 3.8.

The packing may be described as herringbone-like with aromatic CH groups directed towards the aromatic systems of other molecules (closest CH•••C distance is 2.78 Å).

Figure 3.8 Packing diagram for compound 3.3d

3.2.4 Absorption and Emission Spectroscopy of NOPs

UV-vis absorption spectra of 3.3a-g are shown in Figure 3.9. The absorption spectra show UV-vis absorption peaks of the alkyl-NOPs (3.3a and 3.3b), featuring the π-

π* transition both at 333 nm (Figure 3.9, top). In contrast, aryl-NOPs (3.3c-g) show the peaks varied from 353 to 360nm (Figure 3.9, bottom). The red shift (~30nm) of aryl-NOP to that of alkyl-NOP was also observed between alkyl and aryl substituted BOPs.3 This red shift suggested that the aryl R group extended the conjugation length of NOPs, and caused the π electronic delocalization across all p orbitals.

Compared to aryl substituted counterparts of BOPs, which display absorption λmax values between 337-348 nm,3 R-NOPs exhibited the longer wavelength (12-16nm longer)

(Table 3.4), demonstrating that NOPs possessed better conjugation than BOPs. In short, the impact of NOP heterocyclic ring (compared to BOP) for increasing conjugation is smaller than the impact of R group (aryls vs. alkyls).

-6 Table 3.4 Absorption and Emission data of NOPs (5 × 10 M in CH2Cl2)

-1 -1 λmax (nm) , M cm λF,max (nm) Int. (a.u.) ΦF  (ns)

3.3a 333 12398 385 504 0.23 1.24

3.3b 333 10972 381 755 0.26 1.26

3.3c 353 24246 461 516 0.12 0.76

3.3d 356 28654 464 689 0.14 0.75

3.3e 357 28710 465 661 0.13 0.44

3.3f 357 28086 464 633 0.13 0.80

3.3g 360 23566 470 876 0.22 0.84

1000 tBu-NOP 0.08 Ad-NOP 800

0.06 600

Abs. 0.04 400

0.02 Intensity(a.u.) Emission 200

0.00 0 300 350 400 450 500 550 Wavelength(nm)

0.2 1000 C H -NOP 6 5 4-MeC H -NOP 6 5 4-ClC H -NOP 6 5 800 4-BrC H -NOP 6 5 4-MeOC H -NOP 6 5 600

0.1 Abs. 400

200 Intensity(a.u.) Emission

0.0 0 300 400 500 600 700 Wavelength(nm)

Figure 3.9 Absorption and emission spectra of NOPs: 3.3a, 3.3b (top), 3.3c-g (bottom)

-6 (conc. is 5 × 10 M in CH2Cl2)

Compound 3.3 are notably fluorescent under UV light, appearing violet to blue in

CH2Cl2 solvent (Figure 3.10, 0.1 M). As for the absorption spectra, the fluorescence

behavior for these compounds break down into two sets of behavior based on the identity

of the R substituents. The emission maxima of 3.3c-g varied from 461-470 nm, while

3.3a and 3.3b emit around 383 nm (Table 3.4). Fluorescence emission spectra revealed a

significant red shift (~80 nm) of aryl-NOPs emission maxima versus the alkyl-NOPs ones.

In contrast, about 40 nm red shifts are seen when comparing the NOPs and analogous of

BOPs.

While there are significant parallels in the absorption and fluorescent emission

spectra of R-BOPs and R-NOPs, there are striking differences in the measured quantum

3 yields (ΦF). In a series of BOPs , aryl substituted BOPs showed quantum yields between

0.56 to 0.69, which were over ten times greater than alkyl-substituted analogues. By

contrast, all of the R-NOPs not only had significant fluorescence, but it is the alkyl substituted R-NOPs that have the greater quantum yields. Specifically, compounds 3.3a and 3.3b have quantum yield of 0.23 and 0.26, respectively, while 3.3c-f have ΦF in the

range of 0.12-0.14, except 3.3g which is 0.22. The reasons for these observations are not

clear at this time.

Fluorescence lifetime measurements were performed in anhydrous hexane to

exploit the energy transfer and quenching at excited state. Compared to the fluorescence

lifetimes of most aryl-BOPs which around 10-30 ns, the lifetimes of 3.3 are shorter (0.44-

1.26 ns). It can be concluded that the NOPs featuring lower energy of singlet excited

states (S1) than BOPs, which caused shorter fluorescence lifetime of 3.3 than 2.19.

Furthermore, aryl-NOPs (3.3c-g) exhibited shorter lifetimes than alkyl-NOPs (3.3a and b) with 0.44-0.80 ns vs. 1.24-1.26 ns.

O O O P P P

Figure 3.10 Compounds 3.3a-g (0.1 M in CH2Cl2) under the room light and UV light

3.2.5 Electrochemical and computational studies of NOPs

Electrochemical experiments were performed on 3.3 to probe their facility towards

reduction in THF. Cyclic voltammetry was used to measure the reduction under

anhydrous conditions inside a nitrogen-filled drybox, Solutions with a concentration of

0.001M NOPs in THF were used for reduction analyses. A three-electrode system, with

glassy carbon as the working electrode, silver wire as the quasi-reference electrode, and

platinum wire as the counter electrode, was utilized. All scans were performed with 0.1

n M tetrabutylammonium tetrafluoroborate, [ Bu4N][BF4], in THF as the supporting

electrolyte, with a scan rate of 0.1 V/s. Ferrocene was utilized as an internal reference

because of the use of a quasi-reference electrode during analyses. Ferrocene (final

concentration 0.001 M) was added after the initial scans of compounds. The reduction

potentials were thus referenced to the ferrocene/ferrocenium redox couple versus

saturated calomel electrode (E1/2 = 0.55 V vs. SCE). Reversibility was ascertained by

scanning 3.3c at various scan rates (25-200 mV) and generating linear plots of scan rates

versus Ep for ferrocene and 3.3c.

Two types of electrochemical behavior were displayed for the NOPs (Figure 3.11).

The alkyl-NOPs (3.3a and 3.3b) did not show evidence for reduction within the electrochemical window examined. By contrast, aryl substituted R-NOPs 3.3c, 3.3d and

3.3g displayed quasi-reversible reduction waves (ipa/ipc~0.6) between -1.8 to -1.9 vs. SCE

(Table 3.5). As one might expect, as the electron donating ability of the 4-XC6H4 moved

from H to Me and OMe, the reduction became more difficult. These experimental trends

observed on R-NOPs were consistent with the electrochemical research of analogous

BOPs. The initial reduction waves (Epc) of NOPs occurred more readily than counterpart of BOPs,11 which attributed to the NOPs’ lower π* orbital.

0.00003 tBu-NOP Ad-NOP C H -NOP 0.00002 6 5 4-MeC H -NOP 6 4 4-MeOC H -NOP 6 4 0.00001

0.00000 Current (A) -0.00001 Fc/Fc+

-0.00002

0.8 0.4 0.0 -0.4 -0.8 -1.2 -1.6 -2.0 -2.4 Potential vs. SCE (V)

Figure 3.11 Cyclic voltammograms of 3.3a-d and 3.3g (Scan rate is 0.1 V/s, conc. is

0.001M in THF)

Table 3.5 Reduction Potentials for 3.3a-d and 3.3g (V vs. SCE)

R Epc Epa E(pc+pa)/2 E (vs. BOP) (pc+pa)/2

3.3a tBu ------

3.3b Ad ------

3.3c C6H5 -1.92 -1.61 -1.77 -0.13

3.3d 4-MeC6H4 -1.96 -1.67 -1.82 -0.14

3.3g 4-MeOC6H4 -2.02 -1.75 -1.89 -0.14

Many of the above experimental trends observed between sets of electrochemical data of R-NOPs and R-BOPs can be reproduced by DFT calculations. Figure 3.12 shows a comparison of the frontier molecular orbitals of Ph-NOP and Ph-BOP. The nature of the HOMOs and LUMOs are very similar between the pair of compounds. The greatest difference lies in the smaller HOMO-LUMO gap for Ph-NOP (3.39 eV vs. 3.84 eV).

Figure 3.12 MO diagrams for Ph-NOP and Ph-BOP (B3LYP/6-31+G**)

A similar comparison can be made for Ph-NOP and tBu-NOP, in order to illustrate differences between alkyl and aryl substituted NOP compounds. Figure 3.13 shows that the tert-butyl derivative has HOMO and LUMO orbitals that are localized only on the heterocyclic ring system, and has a greater HOMO-LUMO gap (3.97 vs. 3.39 eV). The

0.52 eV higher lying LUMO orbital correlates with the inability to observe the reduction of the alkyl substituted NOP derivatives.

Figure 3.13 MO diagrams for Ph-NOP and tBu-NOP (B3LYP/6-31+G**)

3.3 Conclusions

Seven new fluorescent conjugated materials, 2-R-naphtho(2,3-d)oxaphospholes (R-

t NOPs) (3.3a-g; R = Bu (a), Ad (b), C6H5(c), 4-MeC6H4 (d), 4-ClC6H4 (e), 4-BrC6H4 (f),

4-MeOC6H4 (g)), have been successfully synthesized by cyclocondensation reactions of

benzimidoyl chlorides with 3-phosphino-2-naphthol (3.13). The compounds were

characterized by multinuclear NMR, UV-vis, and fluorescence spectroscopy. Compounds

3.3a-d and 3.3g were characterized by cyclic voltammetry experiments. The solid state

structures of compounds 3.3a and 3.3d were also determined by single-crystal X-ray

diffraction experiments.

3-Phosphino-2-naphthol (3.13) exhibits greater air-stability than most primary

phosphine. And the R-NOPs were also possessed reasonable air and water stability,

especially in the solid state. Single-crystal structures of Ad-NOP (3.3b) and MeC6H4-

NOP (3.3d) both display a coplanar conformation for the heterocyclic ring. Containing aryl substituent, 3.3d exhibits a good coplanar figuration with torsion angle around 175˚.

Furthermore, single crystals of 3.3d packed in herringbone geometry.

The studies of PL displayed that alkyl- and aryl- substituted NOPs exhibited

absorption maxima at 333 nm and around 355 nm, respectively, while they displayed

emission maxima ~383 nm and ~465 nm, respectively. It illustrated the alkyl-NOPs

possess smaller HOMO/LUMO gaps than aryl-NOPs, which was confirmed by DFT

calculations. Compared to BOPs (λmax ~305 nm and λF,max ~370 nm.), NOPs were

observed red shift of both absorption and emission maxima. It was demonstrated that

NOPs performed smaller HOMO/LUMO gaps than counterparts of BOPs, which was

also confirmed by DFT calculations.

Cyclic voltammetry experiments revealed that alkyl-NOPs (3.3a and 3.3b) did not

show evidence for reduction within the electrochemical window examined. By contrast,

aryl substituted R-NOPs 3.3c, 3.3d and 3.3g shown quasi-reversible reduction waves

(ipa/ipc~0.6) between -1.8 to -1.9 vs. SCE. The initial reduction waves (Epc) of NOPs occurred more readily than counterpart of BOPs, which attributed the NOPs’ lower π*

orbital.

PL and electrochemical properties demonstrated that owning good stability, solubility and good photoluminescence, Ph-NOP could be the best candidate to employ in synthesis of π-conjugated polymer and have the potential for use in photo- or electro- devises such as OLEDs.

3.4 Experimental

General Procedures:

Reactions were conducted under nitrogen using either Schlenk line techniques or

within an MBraun drybox. Tetrahydrofuran, toluene and diethyl ether were dried by

distillation from sodium and benzophenone ketyl. Hexanes was dried by distillation from

sodium and benzophenone in the presence of tetraethylene glycol dimethyl ether.

Methylene chloride was dried by distillation from calcium hydride. Methylene chloride

(99.8%, for spectroscopy) and ethanol (200 proof) were degassed prior to use for UV-vis

and fluorescence spectroscopy. Benzimidoyl chlorides were prepared following literature

5 1 31 1 protocols. NMR spectra ( H and P{ H}) were recorded in CDCl3, unless otherwise

noted, on a Varian INOVA AS-400 spectrometer operating at 399.7 and 161.8 Hz,

31 1 13 1 respectively, and P{ H} NMR spectra were referenced to 85% H3PO4. C{ H} NMR spectra were recorded in CDCl3 on a Varian INOVA AS-600 spectrometer operating at

150.9 Hz, unless otherwise noted.

UV-vis and fluorescence spectra were recorded using a Cary-5G-UV-vis-NIR

spectrophotometer and a Cary Eclipse spectrometer, respectively. Anthracene in ethanol

-6 was used as a standard for quantum yield measurements (CH2Cl2, conc. 5 × 10 M). The

excitation slit width for all measurements was kept at default settings (5 nm). Melting

points were measured on a Thomas Hoover Capillary Melting Point

Apparatus. Elemental analyses were performed by Robertson Microlit Laboratories,

Ledgewood, New Jersey. High resolution mass spectrometry was performed by the

University of Michigan Mass Spectrometry facility using a VG (Micromass) 70-250-S

magnetic sector spectrometer with EI technique at 70 eV.

Diethyl(2-naphthyl)phosphate (3.9)

Triethylamine (17.5 mL, 89.7 mmol) was added drop wise to a mixture containing

2-naphthol (10.0 g, 69.4 mmol) and diethyl chlorophosphate (12.1 mL, 83.2 mmol) in

150 mL THF in a 500 mL round bottom flask with a stir bar. The solution was stirred for

12 hours. Aqueous HCl solution (1.2 M, 100 mL) was added, the mixture solution was

stirred until the precipitate disappeared, and 100 mL diethyl ether was added to extract the product. The organic layer was separated and washed successively with degassed solutions of aqueous HCl (1.2 M, 100 mL), aqueous NaOH (1 M, 100 mL), distilled water and was dried over anhydrous sodium sulfate. The solvent was removed by rotary

1 evaporation to yield a brown liquid 3.9 (18.7 g, 95.9%); H NMR (CDCl3): δ 7.79 (m, 3H)

7.69 (s, 1H), 7.43 (m, 2H), 7.36 (m, 1H), 4.23 (m, 4H), 1.34 (m, 6H); 31P{1H} NMR

13 1 (CDCl3): δ -6.1 (s); C{ H} NMR (CDCl3): δ 148.3 (d, JPC = 6.9 Hz), 133.8, 130.8,

129.8, 127.6, 127.5, 126.6, 125.4, 120.0 (d, JPC = 5.3 Hz), 116.3 (d, JPC = 4.8 Hz), 64.6

(d, JPC = 6.0 Hz), 16.1 (d, JPC = 6.6 Hz).

Diethyl(3-hydroxy-2-naphthyl)phosphonate ( 3.12 )

To a solution of diisopropylamid diisopropylamide e (15.1 mL, 107 mmol) in 50

mL THF, at -78 ˚С in a nitrogen atmosphere in a 500 mL round bottom flask with a stir

bar, nBuLi (2.5 M in hexane, 42.8 mL, 107 mmol) was added. The mixture was stirred for

30 minutes to allow white slurry lithium diisopropylamide (LDA) formed. Diethyl (2-

naphthyl) phosphate (3.9, 15.0 g, 53.5 mmol) was dissolved in 25 mL THF in a 50 mL

round bottom flask, and then transferred to LDA by cannula. The mixture solution was

stirred for 2 h at -78 ˚С, brought to room temperature and then poured over saturated

ammonium chloride aqueous solution (250 mL). The solution was stirred for 15 min.

until precipitate was dissolved, and the product was extract with CH2Cl2 300 mL.

Organic layer was separated and washed by distilled water twice, dried over anhydrous

sodium sulfate. The solvent was removed by rotary evaporation to yield brown liquid,

which solidified upon cooling. Clear crystals 3.12 were obtained by dissolving warm

1 hexanes and cooling to -4˚С (5.24 g, 51.4%) H NMR (CDCl3): δ 9.99 (s, 1H, OH) 8.02

3 (d, 1H, JPH = 16.4 Hz), 7.79 (m, 1H), 7.70 (m, 1H), 7.49 (m, 1H), 7.33 (m, 2H), 4.16 (m,

31 1 13 1 4H), 1.35 (m, 6H); P{ H} NMR (CDCl3): δ 21.9 (s); C{ H} NMR (CDCl3): δ 156.7 (d,

JPC = 7.6 Hz), 137.7 (d, JPC = 2.0 Hz), 134.1 (d, JPC = 5.7 Hz), 128.7, 128.6, 127.3 (d, JPC

= 15.3 Hz), 126.5, 123.9, 112.4 (d, JPC = 178.6 Hz), 111.6 (d, JPC = 11.5 Hz), 62.9 (d, JPC

= 4.7 Hz), 16.2 (d, JPC = 6.6 Hz); mp: 110-113˚С; elemental analysis: Calc. for C15H15OP

(M.W. 280.26), C 60.00%, H 6.11%; found: C 60.32%, H 6.17%.

3-phosphino-2-naphthol (3.13)

Diethyl (3-hydroxy-2-naphthyl)phosphonate (3.12, 4.02 g, 14.3 mmol) was added a solution of LiAlH4 (1.09 g, 28.6 mmol) in 100 mL THF in a 500 mL round bottom flask

with a stir bar. The solution was refluxed under nitrogen for 1 hour, an aqueous solution

of saturated ammonium chloride was added drop wise to quench the excess LiAlH4, and product was extracted with chloroform (200 mL). Organic layer was separated, and filtered through celite using glass fritted filter funnel. Solvents were removed by rotary

1 evaporation to yield a white solid 3.13 (2.41 g, 95.6%); H NMR (CDCl3): δ 8.04 (d, 1H,

3 4 JPH = 9.6 Hz), 7.72 (m, 1H), 7.66 (m, 1H), 7.43 (m, 1H), 7.33 (m, 1H), 7.17 (d, 1H, JPH

31 1 = 2.4 Hz), 5.29 (s, 1H, OH), 4.20 (s, 1H, PH), 3.69 (s, 1H, PH); P{ H} NMR (CDCl3):

13 1 δ -148.3 (s). C{ H} NMR (CDCl3): δ 154.4 (d, JPC = 4.7 Hz), 137.4 (d, JPC = 22.3 Hz),

135.4, 128.9 (d, JPC = 8.0 Hz), 127.3, 127.0, 126.1, 123.9, 117.3 (d, JPC = 12.2 Hz), 109.0

(d, JPC = 1.4 Hz); mp: 134-135˚С; elemental analysis: Calc. for C10H9OP (M.W. 176.15),

C 68.18%, H 5.15%; found: C 67.91%, H 5.10%.

2 (tert-butyl)naphtho(2,3-d)oxaphosphole (3.3a)

3-Phosphino-2-naphthol (3.13, 1.00 g, 5.68 mmol) and N-phenylpivalimidoyl

chloride (3.67 g, 18.8 mmol) were added to a 250 mL round bottom flask with a stir bar,

the flask was outfitted with a reflux condenser and flushed with nitrogen, THF (35 mL)

was added by cannula and the solution was refluxed for 15 hours. The reaction mixture

was taken into a dry box, and filtered using glass fritted filter funnel. The solid was

extracted with THF (2 × 5 mL), the combined filtrate was evaporated under vacuum yield

a brown solid. Crude product was purified using column chromatography

(CH2Cl2/hexanes 1:9, Rf = 0.8). Solvent was removed by rotary evaporation to yield a

1 3 white solid 3.3a (0.89 g, 65%); H NMR (CDCl3): δ 8.44 (d, 1H, JPH = 4.0 Hz), 8.09

4 31 1 (s,1H), 7.93 (m, 2H,), 7.47 (m, 2H), 1.52 (d, 9H, JHH = 1.2 Hz); P{ H} NMR (CDCl3):

13 1 δ 74.1 (s); C{ H} NMR (CDCl3): δ 217.6 (d, JPC = 63.6 Hz), 158.6, 136.2 (d, JPC = 38.1

Hz), 132.4 (d, JPC = 2.3 Hz), 129.9 (d, JPC = 9.2 Hz), 128.4 (d, JPC = 19.2 Hz), 127.7,

127.6, 125.8, 124.4, 108.8, 38.4 (d, JPC = 11.8 Hz), 29.7 (d, JPC = 9.1 Hz); UV (CH2Cl2,

-6 -1 -1 -6 5.0 × 10 M): λmax, nm (, M cm ) 333 (12398); fluorescence (CH2Cl2, 5.0 × 10 M):

λex, nm (Int.) 385 (504); quantum yield (CH2Cl2): ΦF 0.23; mp: 77-80˚С; elemental

analysis: calc. for C15H15OP (M. W. 242.25), C 74.37%, H 6.24%; found: C 73.80%, H

6.20%.

2(adamantyl)naphtho(2,3-d)oxaphosphole (3.3b)

3-Phosphino-2-naphthol (3.13, 0.600 g, 3.41 mmol) and N-adamantyl-

phenylbenzimidoyl chloride (1.73 g, 6.32 mmol) were added in a 250 mL round bottom

flask with a stir bar, the flask was outfitted with a reflux condenser and flushed with nitrogen, THF (25 mL) was added by cannula under nitrogen. The solution was refluxed for 15 hours. The reaction mixture was taken into a dry box, and filtered using glass fritted filter funnel. The solid was extracted with THF (2 × 5 mL), the combined filtrate was evaporated under vacuum yield a brown solid. Crude product was purified using column chromatography (CH2Cl2/hexanes 1:9, Rf = 0.8). Solvent was removed by rotary

1 evaporation to yield a white solid 3.3b (0.72 g, 66%); H NMR (CDCl3): δ 8.44 (d, 1H,

3 JPH = 4.0 Hz), 8.07 (s, 1H), 7.93 (m, 2H), 7.46 (m, 2H), 2.13 (s, 9H), 1.83 (s, 6H);

31 1 13 1 P{ H} NMR (CDCl3): δ 72.8(s); C{ H} NMR (CDCl3): δ 217.9 (d, JPC = 62.8 Hz),

158.4, 136.1 (d, JPC = 38.1 Hz), 132.3 (d, JPC = 2.1 Hz), 129.8 (d, JPC = 9.4 Hz), 128.4 (d,

JPC = 19.2 Hz), 127.7, 127.6, 125.7, 124.3, 108.7, 41.8 (d, JPC = 9.4 Hz), 40.3 (d, JPC =

-6 -1 -1 10.9 Hz), 36.7, 28.3 (d, JPC = 1.4 Hz); UV (CH2Cl2, 5.0 × 10 M): λmax, nm (, M cm )

-6 333 (10972); fluorescence (CH2Cl2, 5.0 × 10 M): λex, nm (Int.) 381 (755); quantum

yield (CH2Cl2): ΦF 0.26; mp: 145-147˚С; elemental analysis: calc. for C21H21OP (M. W.

320.36), C 78.73%, H 6.61%; found: C 78.52%, H 6.82%.

2(phenyl)naphtho(2,3-d)oxaphosphole (3.3c)

3-Phosphino-2-naphthol (3.13, 0.350 g, 1.99 mmol) and 4-methoxy-N- phenylbenzimidoyl chloride (1.28 g, 5.93 mmol) were added in a 250 mL round bottom flask with a stir bar, the flask was outfitted with a reflux condenser and flushed with nitrogen, THF (25 mL) was added by cannula under nitrogen. The solution was refluxed for 20 hours, the reaction mixture was taken into a dry box, and filtered using glass fritted

filter funnel. The solid was extracted with THF (2 × 5 mL), the combined filtrate was

evaporated under vacuum yield brown solid. Crude product was dissolved in CH2Cl2 (~75 mL), washed successively with degassed solution of aqueous HCl (1.2 M, 100 mL), aqueous NaOH (1 M, 100 mL) and distilled H2O (100 mL). The solvent was removed

under vacuum to yield yellow solid which was washed with degassed ethanol (~ 150 mL)

and filtered using glass fritted filter funnel. A yellow solid was collected and

recrystallization in toluene at -47 ˚С yielded yellow solid 3.3c (0.150 g, 28.8%); 1H NMR

3 (CDCl3): δ 8.51 (d, 1H, JPH = 3.2 Hz), 8.17 (s, 1H), 8.11 (m, 2H), 7.96 (m, 2H,), 7.47 (m,

31 1 13 1 5H); P{ H} NMR (CDCl3): δ 83.7 (s); C{ H} NMR (CDCl3): δ 199.9 (d, JPC = 55.3

Hz), 158.0, 136.6 (d, JPC = 37.3 Hz), 134.6 (d, JPC = 12.8 Hz), 132.9 (d, JPC = 2.9 Hz),

130.3 (d, JPC = 5.0 Hz), 130.1 (d, JPC = 10.3 Hz), 128.9, 128.7, 127.8, 127.7, 126.1, 125.1

-6 -1 -1 (d, JPC = 14.8 Hz), 124.7, 109.1; UV (CH2Cl2, 5.0 × 10 M): λmax, nm (, M cm ) 353

-6 (24246); fluorescence (CH2Cl2, 5.0 × 10 M): λex, nm (Int.) 461 (516); quantum yield

(CH2Cl2): ΦF 0.12; mp: 173-176˚С; elemental analysis: calc. for C17H11OP (262.24), C

77.86%, H 4.23%; found: C 77.63%, H 4.16%.

2(4-methylphenyl)naphtho(2,3-d)oxaphosphole (3.3d)

3-Phosphino-2-naphthol (3.13, 1.00 g, 5.68 mmol) and 4-methyl-N-

phenylbenzimidoyl chloride (1.95 g, 8.52 mmol) were added in a 250 mL round bottom

flask with a stir bar, the flask was outfitted with a reflux condenser and flushed with

nitrogen, THF (30 mL) was added by cannula under nitrogen. The solution was refluxed

for 20 hours, the reaction mixture was taken into a dry box, and filtered using glass fritted

filter funnel. The solid was extracted with THF (2 × 5 mL), the combined filtrate was

under vacuum to yield a yellow solid which was washed with degassed ethanol (~ 150

mL) and filtered using glass fritted filter funnel. A yellow solid was collected and

recrystallization in toluene at -47 ˚С yielded yellow solid 3.3d (0.910 g, 58.0%); 1H NMR

3 (CDCl3): δ 8.47 (d, 1H, JPH = 2.8 Hz), 8.13 (s, 1H), 7.98 (m, 2H), 7.93 (m, 2H), 7.47 (m,

3 31 1 13 2H), 7.25 (d, 2H, JHH = 5.2 Hz), 2.41 (s, 3H); P{ H} NMR (CDCl3): δ 80.1 (s); C{1H}

NMR (CDCl3): δ 200.3 (d, JPC = 55.6 Hz), 158.0 (d, JPC = 3.5 Hz), 140.7 (d, JPC = 5.0

Hz), 136.8 (d, JPC = 37.1 Hz), 132.8 (d, JPC = 2.6 Hz), 132.0 (d, JPC = 13.0 Hz), 130.1 (d,

JPC = 10.3 Hz), 129.6, 128.6 (d, JPC = 19.2 Hz), 127.7, 127.7, 126.0, 125.1 (d, JPC = 14.6

-6 -1 -1 Hz), 124.6, 109.0, 21.6; UV (CH2Cl2, 5.0 × 10 M): λmax, nm (, M cm ) 356 (28654);

-6 fluorescence (CH2Cl2, 5.0 × 10 M): λex, nm (Int.) 464 (689); quantum yield (CH2Cl2):

ΦF 0.14; mp 170-174˚С; elemental analysis: calc. for C18H13OP (M. W. 276.27), C

78.25%, H 4.74%; found: C 78.36%, H 4.96%.

2(4-chlorophenyl)naphtho(2,3-d)oxaphosphole (3.3e)

3-Phosphino-2-naphthol (3.13, 0.480 g, 2.72 mmol) and 4-chloro-N- phenylbenzimidoyl chloride (2.22 g, 8.87 mmol) were added in a 250 mL round bottom flask with a stir bar, the flask was outfitted with a reflux condenser and flushed with nitrogen, THF (25 mL) was added by cannula under nitrogen. The solution was refluxed for 20 hours, reaction mixture was filtered in dry box and the white precipitate was washed twice with THF. The the reaction mixture was taken into a dry box, and filtered using glass fritted filter funnel. The solid was extracted with THF (2 × 5 mL), the combined filtrate was evaporated under vacuum yield brown solid. Crude product was dissolved in CH2Cl2 (~75 mL), washed successively with degassed solution of aqueous

HCl (1.2 M, 100 mL), aqueous NaOH (1 M, 100 mL) and distilled H2O (100 mL). The

solvent was removed under vacuum to yield a yellow solid which was washed with

degassed ethanol (~ 150 mL) and filtered using glass fritted filter funnel. A yellow solid

was collected and recrystallization in toluene at -47 ˚С yielded yellow solid 3.3e (0.350 g,

1 3 43.2%); H NMR (CDCl3): δ 8.51 (d, 1H, JPH = 4.8 Hz), 8.15 (s,1H ), 8.03 (m, 2H), 7.95

31 1 13 1 (m, 2H), 7.50 (m, 2H), 7.43 (m, 2H); P{ H} NMR (CDCl3): δ 85.8(s); C{ H} NMR

(CDCl3): δ 198.3 (d, JPC = 54.7 Hz), 158.0 (d, JPC = 3.8 Hz), 136.4 (d, JPC = 37.0 Hz),

136.0 (d, JPC = 6.0 Hz), 133.1 (d, JPC = 13.1 Hz), 133.0 (d, JPC = 2.6 Hz), 130.1 (d, JPC =

10.6 Hz), 129.1, 129.0 (d, JPC = 19.0 Hz), 127.8, 127.8, 126.3, 126.3 (d, JPC = 14.9 Hz),

-6 -1 -1 124.8, 109.1; UV (CH2Cl2, 5.0 × 10 M): λmax, nm ( , M cm ) 357 (28710);

-6 fluorescence (CH2Cl2, 5.0 × 10 M): λex, nm (Int.) 465 (661); quantum yield (CH2Cl2):

ΦF 0.13; mp 190-194˚С; elemental analysis: calc. for C17H10ClOPC (M. W. 296.69), C

68.82%, H 3.40%; found: C 69.01%, 3.32%.

2(4-bromophenyl)naphtho(2,3-d)oxaphosphole (3.3f)

3-Phosphino-2-naphthol (3.13, 0.600 g, 3.41 mmol) and 4-bromo-N-

phenylbenzimidoyl chloride (1.86 g, 6.31 mmol) were added in a 250 mL round bottom

flask with a stir bar, the flask was outfitted with a reflux condenser and flushed with nitrogen, THF (30 mL) was added by cannula under nitrogen. The solution was refluxed for 20 hours, the reaction mixture was taken into a dry box, and filtered using glass fritted

filter funnel. The solid was extracted with THF (2 × 5 mL), the combined filtrate was

under vacuum to yield a yellow solid which was washed with degassed ethanol (~ 150

mL) and filtered using glass fritted filter funnel. A yellow solid was collected and

recrystallization in toluene at -47 ˚С yielded yellow solid 3.3f (0.380 g, 32.8%); 1H

3 3 NMR(CDCl3): δ 8.52 (d, 1H, JPH = 4.8 Hz), 8.16 (s,1H ), 7.97 (m, 4H), 7.59 (d, 2H, JHH

31 1 13 1 = 8.4 Hz), 7.50 (m, 2H); P{ H} NMR (CDCl3): δ 86.7 (s); C{ H} NMR (CDCl3): δ

198.3 (d, JPC = 54.8 Hz), 158.0 (d, JPC = 3.6 Hz), 136.4 (d, JPC = 37.0 Hz), 133.5 (d, JPC

= 13.1 Hz), 133.0 (d, JPC = 2.7 Hz), 132.1, 130.2 (d, JPC = 10.3 Hz), 129.0 (d, JPC = 19.2

Hz), 127.8, 127.8, 126.5 (d, JPC = 14.9 Hz), 126.3, 124.9, 124.3 (d, JPC = 6.0 Hz), 109.2;

-6 -1 -1 UV (CH2Cl2, 5.0 × 10 M): λmax, nm (, M cm ) 357 (28086); fluorescence (CH2Cl2,

-6 5.0 × 10 M): λex, nm (Int.) 464 (633); quantum yield (CH2Cl2): ΦF 0.13; mp 202-205˚С;

HRMS m/z: 339.9655 (calc. 339.9653).

2(4-methoxyphenyl)naphtho(2,3-d)oxaphosphole (3.3g)

3-Phosphino-2-naphthol (3.13, 0.500 g, 2.84 mmol) and 4-methoxy-N- phenylbenzimidoyl chloride (1.68 g, 6.84 mmol) were added in a 250mL round bottom flask with a stir bar, the flask was outfitted with a reflux condenser and flushed with nitrogen, THF (25 mL) was added by cannula under nitrogen. The solution was refluxed for 20 hours, the reaction mixture was taken into a dry box, and filtered using glass fritted filter funnel. The solid was extracted with THF (2 × 5 mL), the combined filtrate was evaporated under vacuum yield a brown solid. Crude product was dissolved in CH2Cl2

(~75 mL), washed successively with degassed solution of aqueous HCl (1.2 M, 100 mL),

aqueous NaOH (1 M, 100 mL) and distilled H2O (100 mL). The solvent was removed

under vacuum to yield yellow solid which was washed with degassed ethanol (~ 150 mL)

and filtered using glass fritted filter funnel. A yellow solid was collected and

recrystallization in toluene at -47 ˚С yielded yellow solid 3.3g ( 0.600 g, 72.3%); 1H

3 NMR (CDCl3): δ 8.47 (d, 1H, JPH = 4.8 Hz), 8.13 (s,1H ), 8.05 (m, 2H), 7.94 (m, 2H),

31 1 13 1 7.48 (m, 2H), 6.98 (m, 2H); P{ H} NMR (CDCl3): δ 74.9 (s); C{ H} NMR (CDCl3):

δ 200.2 (d, JPC = 56.2 Hz), 161.4 (d, JPC = 4.8 Hz), 157.9 (d, JPC = 3.2 Hz), 142.0(d, JPC

= 20.1 Hz), 136.9 (d, JPC = 37.3 Hz), 132.7 (d, JPC = 2.4 Hz), 130.1 (d, JPC = 9.8 Hz),

128.4 (d, JPC = 19.3 Hz), 127.7, 127.7, 126.9 (d, JPC = 14.5 Hz), 125.9, 124.6, 114.3,

-6 -1 -1 108.8, 55.5; UV (CH2Cl2, 5.0 × 10 M): λmax, nm (, M cm ) 360 (23566); fluorescence

-6 (CH2Cl2, 5.0 × 10 M): λex, nm (Int.) 470 (876); quantum yield (CH2Cl2): ΦF 0.22; mp

195-198˚С; elemental analysis: calc. for C18H13O2P (M. W. 292.27), C 73.91%, H 4.48%;

found: C 73.40%, H 4.16%.

Fluorescence Lifetimes

Fluorescence lifetime measurements were performed under an atmosphere of dry

nitrogen in a glove box. Approximately 2 mg of each sample was dissolved in 10 mL of

anhydrous hexane to produce samples with optical densities of below 0.05. Each sample

was subsequently filtered through a 0.2 μM PTFE syringe filter into a Spectrosil quartz

cuvette having a path length of 1 cm. Each cuvette was sealed with a PTFE screw cap and

the lifetimes were acquired. Lifetimes of sample solutions were measured using a PTI

Easylife II with an excitation wavelength of 340 nm. A 320 nm low band gap cut off

filter was positioned between the sample and detector for these measurements to

eliminate scattered excitation source light interference.

Crystallographic Studies

Summary of crystal data and collection parameters for crystal structure of 3.12,

3.3b and 3.3d are provided in Table 3.6, and detailed descriptions of data collection as

well as data solution are provided below. Compound 3.12 was done at Department of

Chemistry, Case Western Reserve University, Cleveland, OH 44106, and compounds

3.3b and 3.3d were done at Department of Chemistry and Biochemistry, University of

California, San Diego, La Jolla, CA 92093. Thermal ellipsoid diagrams were generated

with Mercury 2.3 software package. The crystal was transferred to a Bruker AXS APEX

II diffractometer with a CCD area detector, centered in the X-ray beam, and cooled to

170 K using a nitrogen-flow low-temperature apparatus that had been precisely calibrated by a thermocouple placed at the same position as the crystal.

Compound 3.12, X-ray quality crystals were grown at low temperature (- 45˚С) in hexanes. Compound 3.3b, X-ray quality crystals were dissolved in hot diethyl ether and grown at room temperature in dry box. Compound 3.3d, X-ray quality crystals were dissolved in hot CH2Cl2 and grown at room temperature in dry box.

Table 3.6 Crystal data and collection parameters of 3.12, 3.3b and 3.3d

3.12 3.3b 3.3d formula C14H12O4P C21 H21OP C18H13OP fw 275.21 320.35 276.25 space group P2(1)/c P2(1)2(1)2(1) P2(1) temperature 170 100 100

(K) a (Å) 9.6672(1) 6.5436(1) 11.755(1) b (Å) 11.5278(2) 13.3825(1) 7.3511(2) c (Å) 12.8735(2) 18.4075(2) 16.433(1)

α (deg) 90.00 90.00 90.00

β (deg) 102.6630(10) 90.00 108.790(3)

γ (deg) 90.00 90.00 90.00

V (Å3) 1399.7(2) 1611.94(2) 1344.3(4)

Z 4 4 4 densitycalc 1.306 1.320 1.365

(g/cm3) radiation Mo Kα (λ = 0.71073 Mo Kα (λ = 0.71073 Mo Kα (λ =

Å) Å) 0.71073 Å) monochromator graphite graphite graphite detector CCD area detector CCD area detector CCD area

detector no. of reflns hemisphere hemisphere hemisphere measd

2 θ range (deg) 4.8-55.9 6.60-50.74 5.24-61.4 cryst dimens 0.42 × 0.29 × 0.10 0.26 × 0.25 × 0.20 0.29 × 0.24 ×

(mm) 0.08 no. of reflns 16803 4287 10573 measd no. of unique 3362 2336 6734 reflns no. of 3362 2336 6734 observations no. of params 177 209 363

R, Rw, Rall 0.0513, 0.1702, 0.0551 0.0425, 0.1110, 0.0462 0.0528, 0.1239,

0.0772

GOF 1.132 1.070 1.012

100

Electrochemical and Computational Studies of NOPs

Cyclic voltammetry experiments were performed in a nitrogen-filled MBraun drybox outfitted with a CH Instrument workstation (CHI630C) at room temperature.

n Tetrabutylammonium tetrafluoroborate, [ Bu4N][BF4], was recrystallized five times using

ethyl acetate and ether, dried thoroughly under vacuum, and stored in the drybox.

Ferrocene was purified by sublimation under vacuum and stored in the drybox. All

glassware was oven-dried overnight before use. A glassy carbon working electrode was

polished with 0.05μm alumina and thoroughly cleaned and dried before use. A silver wire

was utilized as a quasi-reference electrode, and a platinum wire was the counter electrode.

All scans were performed at a scan rated of 0.1 V/s unless otherwise stated. All spectra

were referenced to SCE using ferrocene as an internal standard.

Solutions with a concentration of 0.001M NOPs in THF were used for reduction

analyses. A three-electrode system, with glassy carbon as the working electrode, silver

wire as the quasi-reference electrode, and platinum wire as the counter electrode, was

utilized. All scans were performed with 0.1 M tetrabutylammonium tetrafluoroborate,

n [ Bu4N][BF4], in THF as the supporting electrolyte, with a scan rate of 0.1 V/s. Ferrocene

was utilized as an internal reference because of the use of a quasi-reference electrode

during analyses. Ferrocene (final concentration 0.001 M) was added after the initial scans

of compounds. The reduction potentials were thus referenced to the ferrocene/ferrocenium redox couple versus saturated calomel electrode (E1/2 = 0.55 V vs.

SCE). Reversibility was ascertained by scanning compounds 3.3c at various scan rates

(25-200 mV) and generating linear plots of scan rates versus Ep for both ferrocene and

compound 3.3c.

101

0.75

0.70

0.65

0.60 Reduction 0.55 Oxidation

0.50 Current (A) Current

0.45

0.40

0.35 468101214 Scan Rate 1/2 (V1/2 in mV/s)

Figure 3.14 Scan rate vs. Ep plot of ferrocene redox couple

-1.55

-1.60

-1.65

-1.70

-1.75 Reduction

-1.80 Oxidation

-1.85 Current (A) Current -1.90

-1.95

-2.00

-2.05 468101214 Scan Rate 1/2 (V1/2 in mV/s)

Figure 3.15 Scan rate vs Ep plot of the redox couple of compound 3.3c

102

0.00004 25 mV/s 50 mV/s 0.00003 75 mV/s 100 mV/s 125 mV/s 0.00002 150 mV/s 175 mV/s 0.00001 200 mV/s Increasing Scan Rate

0.00000 Current (A) Current

-0.00001 Fc/Fc+

-0.00002

1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -2.5 Potential vs. SCE (V)

Figure 3.16 Variable scan rate voltammogram for compound 3.3c

(Scan rates of 25 to 200 mV/s, conc. is 0.001 M in THF)

103

3.5 Works Cited

(1) Laughlin, F. L.; Rheingold, A. L.; Deligonul, N.; Laughlin, B. J.; Smith, R.

C.; Higham, L. J.; Protasiewicz, J. D. Dalton Transactions 2012, in press.

(2) Heinicke, J.; Tzschach, A. Phosphorus Sulfur Relat. Elem. 1985, 25, 345.

(3) Washington, M. P.; Gudimetla, V. B.; Laughlin, F. L.; Deligonul, N.; He,

S.; Payton, J. L.; Simpson, M. C.; Protasiewicz, J. D. J. Am. Chem. Soc. 2010, 132, 4566.

(4) Dhawan, B.; Redmore, D. J. Org. Chem. 1991, 56, 833.

(5) Van, d. N. A. M. C. H.; Pietra, D.; Heitman, L.; Goeblyoes, A.; Ijzerman,

A. P. J. Med. Chem. 2004, 47, 663.

(6) Anthony, J. E. Chem. Rev. 2006, 106, 5028.

(7) Okamoto, T.; Jiang, Y.; Qu, F.; Mayer, A. C.; Parmer, J. E.; McGehee, M.

D.; Bao, Z. Macromolecules 2008, 41, 6977.

(8) Jiang, Y.; Okamoto, T.; Becerril, H. A.; Hong, S.; Tang, M. L.; Mayer, A.

C.; Parmer, J. E.; McGehee, M. D.; Bao, Z. Macromolecules 2010, 43, 6361.

(9) Hsu, D.-T.; Lin, C.-H. J. Org. Chem. 2009, 74, 9180.

(10) Wang, H.; Schaffner-Hamann, C.; Marchioni, F.; Wudl, F. Adv. Mater.

2007, 19, 558.

(11) Washington, M. P.; Payton, J. L.; Simpson, M. C.; Protasiewicz, J. D.

Organometallics 2011, 30, 1975.

(12) Dhawan, B.; Redmore, D. J. Org. Chem. 1986, 51, 179.

(13) Taylor, C. M., Watson, A. J. Curr. Org. Chem. 2004, 8, 623.

(14) Heinicke, J. T., A. phosphorus and Sulfur, 1985, 25, 345.

104

(15) Gorenstein, D. G.; Editor Phosphorus-31 NMR: Principles and

Applications; Academic Press, 1984.

(16) Stewart, B.; Harriman, A.; Higham, L. J. Organometallics 2011, 30, 5338.

(17) Higham, L. J. Catal. Met. Complexes 2011, 37, 1.

(18) Rauhut, M. M.; Currier, H. A. J. Org. Chem. 1961, 26, 4626.

105

Chapter 4: Synthesis and Characterization of Naphthobisoxaphospholes (NBOPs)

4.1 Introduction

Naphthobisoxaphospholes (NBOPs) are heterocyclic conjugated compounds which contain a naphthalene ring fused with two oxaphospholes (OPs). There are five type of possible isomers, I-type (I), J-type (II), U-type (III), S-type (IV) and Y-type (V) (Figure 4.1), which are classified according to the molecular shapes (this nomenclature is adopted by analogy to that used for naphthodithiophenes1). Each type of structure also could have additional isomers when the naphthalene ring fused two OPs on different positions, for instance, Figure 4.2 shows three isomers (IVa-c) for S-type of NBOP.

O O O P O P P P O O P P I, I-type II, J-type III, U-type

O P P O

P O O P

IV, S-type V, Y-type

Figure 4.1 Different isomers of naphthobisoxaphospholes (NBOPs)

106

Figure 4.2 Isomers of S-type of NBOP

Scheme 4.1 Potential synthesis routes for different NBOP isomers

Based upon similar synthetic routes to BBOPs2 and NOPs,3 different NBOP isomers could conceivably be obtained via different starting materials. For instance, four compounds could be synthesized by the routes shown in Scheme 4.1, starting with two types of naphthylenediols (4.1 and 4.6), respectively. Route (1) starts by phosphorylating 1,5-

107 dihydroxynaphthylene (4.1) with diethyl chlorophosphate, followed by an anionic double phospho-Fries rearrangement, which transforms the bis(phosphate) (4.2) into the single product bis(phosphonate) (4.3). In contrast, potential routes (2)-(4) start from phosphorylating same start material, 2,6-dihydroxynaphthylene (4.6), with diethyl chlorophosphate, followed by an anionic double phospho-Fries rearrangement, which transforms the bis(phosphate) (4.7) into the mixture products, 4.8, 4.11 and 4.14.

Considering the mixture of bis(phosphonate)s, 4.8, 4.11 and 4.14, that could potentially be produced from 4.7, and subsequent the difficulty of isolating and purifying these compounds, 4.3 as our initial investigation choose to pursue. It would be single product after phospho-Fries rearrangement in route (1), and would easily be isolated with higher yield.

Thus 4.5, the S-type NBOP (IVa), was selected as the initial target heterocyclic ring compound to investigate.

Figure 4.3 Structure of S-type heterocyclic compounds

The study of S-type heterocyclic acene-like compounds with oxygen and sulfur atoms

(VI and VII, Figure 4.3) began in the middle of last century.4 Naphthodithiophenes (NDTs) are heterocyclic compounds consisting of two thiophenes fused on the end of naphthalene. In

1951, compound S-type of NDTs 4.17 (Figure 4.4) was first reported by Tilak but without 108 physical data.4 Although studies of synthesis and characterization of analogous compounds

4.18 and 4.19 were published later,5-7 it seems NDTs did not attract significant attention possibly because the lack of practical methods for the scalable synthesis inhibited further investigations. In 2009, Umeda attempted to prepare compounds 4.18 and 4.20 via flash vacuum pyrolysis (FVP), however, these compounds could not be isolated in a pure state.1

Figure 4.4 Naphthodithiophenes (NDTs) with S- and U-type structures

In 2010, Takimiya and co-workers reported the synthesis of compounds 4.21a-c

(Figure 4.5) via four step method with good yields (a, 90%, b, 89%, c, 60%).8 These compounds were characterized, and the results indicated that they could potentially be applied on organic semiconducting materials, such as OFETs. Employing this highly rigid coplanar building block, Takimiya and Osaka prepared the novel semiconducting polymers

(4.22a-e) (Figure 4.5).9 The introduction of thiophene-based rings as well as donor-acceptor systems into the polythiophene backbone was a promising approach for enhancing the intermolecular π overlap and thus the π stacking. Consequently, these coplanar polymers 4.22 exhibited field-effect mobilities as high as 0.5 cm2 V-1 s-1 and maximum current on/off ratios

8 (Ion/Ioff) of up to 10 in OFET devices, which were stated to be among the best values of field- effect mobilities at that time.

109

Figure 4.5 S-type of naphthodithiophenes (NDTs) 4.21 and 4.22

In 2012, considering the symmetrical planar structure and higher mobility of 4.21 and

4.22, Lee and co-workers incorporated an alternating donor-acceptor conjugated unit into the

NDT unit and synthesized 4.23a-d (Figure 4.6) by stepwise Pd-catalyzed Suzuki and Stille coupling reactions.10,11 These materials efficiently reduced the HOMO/LUMO gaps, substantially extended conjugation and enhanced π-π stacking, while the long side chain would increase solubility and processability, consequently, improving both charge generation and transportation for photovoltaic applications.

110

Figure 4.6 S-type of naphthodithiophenes (NDTs) 4.23

The first S-type naphtho[2,1-b; 6,5-b’]difuran (VIa) (Figure 4.3) was synthesized in

1966 by Kuriakose and co-worker,12 and the first S-type naphtho[2,1-b; 5,6-b’]difuran (VIb) was synthesized by Gogte and co-workers with other Y-, U-, I- and J-type NDFs in 1971.13

As same as the counterparts of NDTs (VIb and VIIb), NDFs (VIa and VIIa) have received far less attention in organic electronics research as the conjugated materials have until recently. Jørgensen and co-workers followed and extended Gogte’s studies and reported the synthesis of 4.24a-k (Figure 4.7).14 Among of these compounds, some of them were doubly substituted with octyl chains to enhance the solubility, which allowed further modification of the aryl groups to attach electron-withdrawing groups.

111

Figure 4.7 S-type naphthodifuran (NDF) 4.24

Furthermore, Tsuji, Takeya and Nakamura reported 4.25 (Figure 4.8), which served as a novel and effective motif for single-crystal OFETs made by a solution- and vapor-growth method. It was notabe that 4.25 showed carrier mobilities of up to 3.6 cm-2 V-1 s-1 as well as high Ion/Ioff ratios-values among the highest for solution-processed OFETs. The computational studies also revealed that the HOMO energy level of NDFs is much higher than that of NDTs when they are both in S-type structures (NDTs, EHOMO ~ -5.8 eV, NDFs,

EHOMO = -5.6 eV). The difference in electronic structure in the ground state could be explained by distinct electronic perturbation from the outermost aromatic rings.15 Therefore, such high performance of NDF-based OFETs illustrated that the potential applications of furans in organic conjugated electronics needs further exploration in the future.

Figure 4.8 S-type naphthodifuran (NDF) 4.25

112

Compared to the NDFs and NDTs, Dicyclopentanaphthalene has attracted limited interest, only 4.26 (Figure 4.9) was published in 2001 by Manríquez and co-workers.16 The complex 4.26 was characterized by cyclic voltammetry and showed two quasi-reversible redox processes, with oxidation peaks at 0.15 and 0.51 V vs. SCE and reduction peaks at 0.31 and -0.06 V vs. SCE. The difference of potential between the oxidation peaks was 360 mV, which indicated moderate electronic interaction between the iron atoms. A UV-Vis-NIR spectrum was recorded and an absorption band at 850 nm was observed, which was assigned to an intervalence band. However, no application of 4.26 was mentioned by the authors.

Figure 4.9 Dicyclopentanaphthalene (4.26), analogue of NDF

Naphtho[1,2-d:5,6-d’]bisoxazole (NBOZ) (4.27a) (Figure 4.10), the close analogue of naphtho[1,2-d:5,6-d’]bisoxaphosphole (NBOPs), has not been investigated. The other isomer, naphtho[2,1-d:6,5-d’]bisoxazole (4.27b), was reported a few times in the 1970s.17,18

113

Figure 4.10 Naphtho[1,2-d:5,6-d’]bisoxazoles and Naphtho[2,1-d:6,5-d’]bisoxazoles

In this work, the design, synthesis and characterization of 2,7-di-R-naphtho[1,2-d:5,6- d’]bisoxaphospholes (R2-NBOPs) is reported. This investigation expands the studies of R-

BOPs, R2-BBOPs and R-NOPs, and towards a series of electron deficient coplanar materials featuring P=C bonds.

114

4.2 Results and Discussion

4.2.1 Synthesis

Three new compounds, 2,7-di-R-naphtho[1,2-d:5,6-d’]bisoxaphosphole (R2-NBOP)

t ( Bu2-NBOP (4.5a), Ad2-NBOP (4.5b), Ph2-NBOP (4.5c)), were prepared via reaction of 2,6- diphosphino-1,5-naphthylenediol (4.4) with N-substituted-benzimidoyl chlorides

R(Cl)C=NPh (R = tBu (4.30a), Ad (4.30b) and Ph (4.30c)) (Scheme 4.2).

Scheme 4.2 Synthesis of 2,7-di-R-naphtho[1,2-d:5,6-d’]bisoxaphospholes (R2-NBOPs)

Secondary phenyl amides (4.29a-c) and imidoyl chlorides (4.30a-c) are known compounds and were prepared as discussed in previous chapter.19

The synthesis route to 4.4 was based on reported methods starting from commercially available 1,5-dihydroxynaphthylene (4.1). The reaction of 4.12 with diethyl chlorophosphate using triethylamine (Et3N) as base in THF products a brown solid tetraethyl(1,5- naphthylene)bis(phosphate) (4.2) in 84.4% yield. It was subjected to the anionic double phospho-Fries rearrangement,20-22 to provide brown solid tetraethyl(1,5-dihydroxy-2,6- 115 naphthylene)bis(phosphonate) (4.3) in 89.0% yield. As expected a single product of phospho-

Fries rearrangement is formed. White solid 2,6-diphosphino-1,5-naphthylenediol (4.4) was obtained by reduction of 4.3 by lithium aluminum hydride (LiAlH4) in THF at room temperature, and in 95.6% yield. Notably, the compound 4.4 displayed great air stability.

Cyclocondensation of benzimidoyl chlorides with 4.4 in THF produced compounds

4.5a-c. The average yields of 4.5a-c (a, 27%, b, 47%, c, 11%) were lower than NOPs (29-

72%) and BBOPs (31-79%), which is attribute in part to the low solubility of 4.5a-c and the difficulty in purifying the products from similarly soluble starting materials and the anilinium salts. Compounds were isolated as white (4.5a-b) and yellow (4.5c) solids

4.2.2 NMR spectroscopic studies

Compounds 4.2-4.5 were characterized by nuclear magnetic resonance (NMR) spectroscopy, which include 31P{1H}, 1H and 13C{1H} NMR spectroscopy. The 31P{1H}

NMR chemical shifts for 4.2-4.5 were typical for phosphate, phosphonate and primary phosphine at -5.3 ppm, 23.6 ppm and -156.3 ppm, respectively.2,3,23 These values are consistent to the NOP project, which display the chemical shift of phosphate (3.9), phosphonate (3.12) and phosphine (3.13) at -6.1 ppm, 21.9 ppm, and -148.3 ppm, respectively(compounds structure see Figure 4.11).3

116

Figure 4.11 Structure of phosphate, phosphonate and primary phosphine

31 1 The comparison of P{ H} NMR data between R-NOPs (3.3) and R2-NBOPs (4.5) is shown in Table 4.1. For compounds 4.5, chemical shift are consistent 7 ppm down field versus to counterparts of 3.3. For R2-BBOPs, by 1-2 ppm down field versus to counterparts of R-BOPs is also observed (Table 4.2).2 Compared to the 1-2 ppm down field chemical shift of R2-BBOPs versus R-BOPs, the 7 ppm down field chemical shift of R2-NBOPs versus R-

NOPs revealed that inductive effect of the naphthalene ring is larger than for benzene ring.

31 1 Table 4.1 P{ H} NMR (CDCl3) data of R-NOPs and R2-NBOPs

3 Substituent (R) R-NOP R2-NBOP /ppm

tBu 74.1 81.8 6.7

Ad 72.8 80.5 7.7

C6H5 83.7 91.6 7.9

117

Table 4.2 31P{1H} NMR data of BOPs and BBOPs

R BOP (ppm) BBOP (ppm) /ppm

tBu 76.424 78.1 1.7

Ad 75.52 76.7 1.2

Ph 86.325 -- --

1 The H NMR (CDCl3) spectra of 4.5 display two sets of peaks, one is associated aromatic protons (H3 and H4 in Figure 4.15) which appear around 8.1 ppm, while another set of peaks corresponding the alkyl substituents show up between 1-3 ppm. For example, the 1H

NMR spectrum of compound 4.5a (Figure 4.12) shows the chemical shift for H3 and H4 at

8.2 ppm (dd) and 8.0 ppm (dd), respectively and the chemical shift of tert-butyl group at 1.5 ppm (d).

Figure 4.12 1H NMR spectrum of 4.5a 118

13 1 There are six NBOP ring peaks observed for the C{ H} NMR (CDCl3) spectra for 4.5.

The chemical shift of carbon in the C=P bond (C6 in Figure 4.13) is around 200 ppm and is a doublet due to the phosphorus atom splitting. The coupling constant for C6 is about 63 Hz for alkyl substituents and 55 Hz for phenyl substituent. It was also consist with 13C{1H} NMR data of 3.3 (Table 4.3).3

Figure 4.13 Structure of R2-NBOP with carbon position numbers

13 1 Table 4.3 C{ H} NMR (CDCl3) data for C=P atoms of R2-NBOP compared to R-NOPs

3 R2-NBOPs (4.5) R-NOPs (3.3)

C=P/ppm J value/Hz C=P/ppm J value/Hz

tBu 212.4 63.6 217.6 63.6

Ad 212.8 62.7 217.9 62.8

C6H5 196.0 55.7 199.9 55.3

4.2.3 Decomposition studies

Compound 4.5 possessed great air and water stability than analogues, BBOPs and

31 1 NOPs. P{ H} NMR spectroscopy (400 MHz) in chloroform-d (CDCl3) was utilized for

119

t t t assessing stabilities of Bu2-BBOP (2.28a), Bu-NOP (3.3a) and Bu2-NBOP (4.5a) (Figure

31 1 t 4.14). P{ H} NMR spectra of solution of Bu2-BBOP (2.28a) in CDCl3 open to air revealed that the signal for 2.28 disappears completely in 5 days (Figure 4.15). The signal for tBu-

t NOP (3.3a) completely disappears in 28 days (Figure 4.16). For Bu2-NBOP (4.5a), phosphorus NMR signal remaining in 60 days is about 80% (Figure 4.17). Notable that it is necessary to refill CDCl3 solvent when it evaporated.

Figure 4.14 Structure and stability of 2.28a, 3.3a and 4.5a

120

31 1 t Figure 4.15 Time-dependent P{ H} NMR spectra of Bu-BBOP (2.28a) in CDCl3 open to

air

121

31 1 t Figure 4.16 Time-dependent P{ H} NMR spectra of Bu-NOP (3.3a) in CDCl3 open to air

122

31 1 t Figure 4.17 Time-dependent P{ H} NMR spectra of Bu2-NBOP (4.5a) in CDCl3 open to air

123

4.2.4 Single Crystal X-ray Diffraction Crystallography

Single crystals suitable for an X-ray diffraction study were obtained from diethyl ether

(4.4 and 4.5a) and CH2Cl2 (4.5c) at room temperature by slow evaporation. The single-crystal structure of 4.4 is shown in Figure 4.18, and packing diagram is shown in Figure 4.19. The phosphorus and oxygen sit on the plane of the naphthalene ring with torsion angle P1-C2-C3-

C4 is 178.7˚ and O1-C3-C2-C1 is 177.2˚. The coplanar structure and intermolecular O•••HO hydrogen bonding leads 4.4 a layer packing structure (Figure 4.19).

Figure 4.18 Thermal ellipsoid diagram of 2,6-diphosphino-1,5-naphthylenediol (4.4)

124

Figure 4.19 Packing diagram for 4.4

The single-crystal structures of 4.5a and 4.5c are shown in Figures 4.20 and 4.21, and selected bond lengths (Å) and bond angles (˚) are shown in Table 4.4. The P=C bond lengths of 1.7050(13) Å (4.5a) and 1.729(3) Å (4.5c), respectively, are consistent with such distances

26 t 2 found in ClC6H4-BOPs (1.712(7) Å) or Bu2-BBOPs (1.694(1) Å) (Table 4.5).

The torsion angle between heterocyclic ring and substituted phenyl ring in 4.5c (P1-C6-

C7-C8) is 177.3˚, which revealed the compound is essentially planar. Considering the significance of crystal packing arrangement for coplanar pentacene-like heterocyclic compounds,27-30 the packing structure of 4.5a (Figure 4.22) and 4.5c (Figure 4.23) were also examined. The molecule of 4.5a packed in herring bone geometry, with aromatic CH group directed towards the π-conjugated systems of other molecules. The distance of CH•••C interactions is 3.26 Å. The π-stacks of 4.5c in columns parallel to the a-axis with only 3.49 Å separating the molecules.

125

Figure 4.20 Thermal ellipsoid diagram of 2,7-di-tert-butyl-naphtho[1,2-d:5,6- d’]bisoxaphosphole (4.5a)

Figure 4.21 Thermal ellipsoid diagram of 2,7-di-phenyl-naphtho[1,2-d:5,6-

d’]bisoxaphosphole (4.5c)

126

Table 4.4 Selected bond lengths (Å) and bond angles (˚) for compounds 4.5a and 4.5c

4.5a 4.5c

P=C 1.7050(13) 1.729(3)

P-C 1.7853(13) 1.788(3)

C-P-C 88.15(6) 87.87(14)

Torsion angle -- 177.3 P1-C6-C7-C8

Table 4.5 P=C bond lengths (Å) for some other oxaphosphole compounds

3 26 t 2 MeC6H4-NOP BrC6H4-BOP Bu2-BBOPs

P=C bond length (Å) 1.716(3) 1.712(7) 1.694(1)

Figure 4.22 Packing diagram for compound 4.5a

127

Figure 4.23 Packing diagram for compound 4.5c

4.2.5 UV-vis Absorption and Fluorescence Emission

The UV-vis absorption spectra for 4.5a-c are shown in Figure 4.24, and the absorption and photoluminescence data shown in Table 4.6. The absorption spectra displayed one π-π* transition peak for the alkyl-NBOPs, 4.5a and 4.5b, at 316 nm and 318 nm, respectively. In contrast, aryl-NBOP (4.5c) showed two peaks at 372 nm and 387 nm with larger molar absorptivity coefficient value (ߝ = 448300 M-1 cm-1).

128

tBu -NBOP 2 0.25 Ad -NBOP 387 nm 2 Ph -NBOP 372 nm 2 0.20

0.15 316 nm 318 nm Abs. 0.10

0.05

0.00 300 400 Wavelength (nm)

-6 Figure 4.24 UV-vis absorption spectra of R2-NBOPs (4.5a-c) (conc. 5.0 × 10 M in CH2Cl2)

-6 Table 4.6 UV-vis and fluorescence of NOPs (4.5a-b conc. 5.0 × 10 M in CH2Cl2, for the

-7 fluorescence of 4.5c, conc. 5.0 × 10 M in CH2Cl2)

-1 -1 λmax (nm) ߝ, M cm λF,max (nm) Int. (a.u.) ΦF

4.5a 316 24600 386 410 0.07

4.5b 318 24300 387 461 0.08

4.5c 387 44800 422 960 0.63

The significant red shift of absorption maximum of Ph2-NBOP to that of alkyl-NBOPs

(~70 nm) was also observed between alkyl and aryl substituted BOPs, BBOPs and NOPs

129

(Table 4.7).2,3,24 This red shift suggested that when two phenyl groups were substituted on

NBOP, it extended the conjugation length, and thus decreased the HOMO/LUMO gaps.

However, considering 20 nm red shift of tBu-NOP to Ph-NOP, the significant ~70 nm red

t shift of Bu2-NBOP to Ph2-NBOP illustrated that NBOP contributed to a greater reduction of

HOMO/LUMO gaps.

-6 t Table 4.7 UV-vis absorption λmax (conc. is 5.0 × 10 M in CH2Cl2, except Bu-BOP, in

CH3OH) (Aryl = C6H5, except aryl-BBOP, Aryl = 2,4,6-Me3-C6H2)

24 2 3 λmax of BOP λmax of BBOP λmax of NOP λmax of NBOP R (nm) (nm) (nm) (nm)

tBu 272 304 333 316

Aryl 337 337 353 387

Compounds 4.5 are notably fluorescent under UV light appearing blue (Figure 4.25, example of 4.5c). Fluorescence emission spectra reveal that 4.5a and 4.5b exhibit three emission peaks around 352nm, 369nm and 387nm, respectively (Figure 4.26). There are small red shift of NBOPs on emission maxima (λF,max) (4.5a, 386 nm, 4.5b, 387 nm) to that of NOP counterparts (Table 4.8). In contrast, 4.5c displayed only one broad peak at 422 nm

-7 with high intensity (conc. is 5.0 × 10 M for 4.5c in CH2Cl2, ten times more dilute than 4.5a and 4.5b). However, this broad peak exhibited ~40 nm blue shift compared to Ph-NOPs

3 (λF,max = 461 nm, Table 4.8). It is notable that the quantum yield of 4.5c (ΦF = 0.63) (Table

4.6) are about eight times higher than other two alkyl-NBOP (4.5a, ΦF = 0.07; 4.5b, ΦF =

0.08).

130

Figure 4.25 Solution of 4.16c (0.5 M in CH2Cl2) under room light and UV light (λF,max = 422

nm)

131

1000 422 nm tBu -NBOP 2 Ad -NBOP 369 nm 2 800 Ph -NBOP 2 368 nm conc. 5.0 x10-7 M 600 352 nm 351 nm 387 nm 386 nm 400 Emission Intensity (a.u.) 200

0 350 400 450 500 550 Wavelength (nm)

Figure 4.26 Fluorescence emission spectra of NBOPs (4.5a-c) (conc. is 5.0 × 10-6 M for 4.5a

-7 and 4.5b, and conc. is 5.0 × 10 M for 4.5c in CH2Cl2)

Table 4.8 Fluorescence emission data (nm) of NOPs and NBOPs (conc. 5.0 × 10-6 M in

CH2Cl2)

3 Substitution (R) λF,max (nm), R-NOPs λF,max (nm), R2-NBOPs

tBu 385 386

Ad 381 387

C6H5 461 422

132

4.2.6 Cyclic Voltammetry

Electrochemical experiments were performed on 4.5a and 4.5c to probe their reduction potential in THF. Solution with compound 4.5a and 4.5c (conc. 0.001 M) in THF with a three-electrode system (glassy carbon as the working electrode, silver wire as the quasi- reference electrode, and platinum wire as the counter electrode) was utilized. All scans were

n performed with 0.1 M tetrabutylammonium tetrafluoroborate ([ Bu4N][BF4]) in THF as the supporting electrolyte, with a scan rate of 0.1 V/s. Ferrocene was utilized as an internal reference because of the use of a quasi-reference electrode during analyses. Ferrocene (final conc. is 0.001 M) was added after the initial scans of compounds. The reduction potentials were thus referenced to the ferrocene/ferrocenium redox couple versus saturated calomel electrode (E1/2 = 0.55 V vs. SCE).

t The Bu2-NBOP (4.5a) did not show evidence for reduction within the electrochemical window examined, as same as the alkyl substituted counterparts of BOPs31 and NOPs19

(Figure 4.27). In contrast, Ph2-NBOP (4.5c) featured an irreversible reduction wave whereas the initial reduction potential (Epc ) at -1.90 V vs. SCE (Figure 4.27).

The reduction potential for 4.5c (Epc = -1.90 V) shifts negative by 120 mV on changing

31 to Ph-BOP (Epc = -2.02 V), and by 20 mV on changing to Ph-NOP (Epc = -1.92 V) (Table

4.9).19 It demonstrated that 4.5c is a good electron acceptor due to it features a lowest π* energy level among these compounds.

133

0.000040

0.000035 0.000030 tBu -NBOP 2 0.000025 Ph -NBOP 2 0.000020

0.000015

0.000010

0.000005 Current (A) 0.000000

-0.000005

-0.000010 Fc/Fc+ -0.000015

-0.000020 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -2.5 Potential Vs. SCE (V)

Figure 4.27 Overlaid cyclic voltammograms for 4.5a and 4.5c

(Scan rate is 0.1 V/s, conc. is 0.001M in THF)

Table 4.9 Reduction potentials (conc. is 0.001M in THF, V vs. SCE)

Epc Epa E(pc+pa)/2 Epc

Ph-BOP31 -2.02 -1.77 -1.90 --

31 (2,4,6-Me3-C6H2)2-BBOP -2.12 -1.89 -2.01 -2.48

Ph-NOP19 -1.92 -1.61 -1.77 --

Ph2-NBOP -1.90 ------

134

Conclusions

In conclusion, three new conjugated molecules NBOPs (4.5a-c), containing P=C bonds along the naphthayl backbone, have been synthesized and characterized. Two of NBOPs contain alkyl substituents (4.5a-b) and one contains aryl substituents (4.5c). All the compounds were fully characterized by NMR, UV-vis and fluorescence spectroscopy. 4.5a and 4.5c have been characterized by CV and X-ray single-crystal structure experiments.

Compound 4.5a possessed significant air and water stability even in solution for weeks.

It demonstrates that NBOPs are more stable than BOPs or NOPs. Single-crystal structures of t Bu2-NBOP (4.5a) and Ph2-NBOP (4.5c) display coplanar configurations for the heterocyclic ring. Compound 4.5c containing phenyl substituent exhibits a completely coplanar figuration.

The studies of PL show that alkyl- and aryl- substituted NBOPs exhibited blue fluorescent color. The absorption spectra displayed one absorption peak for the alkyl-NBOPs,

4.5a and 4.5b, featured the π-π* transition at 316 nm and 318 nm, respectively. In contrast,

Ph2-NBOP (4.5c) showed two peaks at 372 nm and 387 nm. A red shift of absorption maxima were also observed between alkyl and aryl substituted NBOPs, however the value is significant (~70 nm) compared to BBOPs (~30 nm) or NOPs (~20 nm). It illustrated the Ph2-

NBOP possess much smaller HOMO/LUMO gaps than alkyl-NBOPs.

Fluorescence emission spectra depicted that 4.5a and 4.5b exhibited three emission peaks around 352 nm, 369 nm and 387 nm, respectively. In contrast, 4.5c displayed only one broad peak at 422 nm with high intensity. It is notable that the quantum yield of 4.5c (ΦF =

0.63) are about eight times higher than other two alkyl substituted compounds (4.5a, ΦF =

0.07; 4.5b, ΦF = 0.08).

135

Cyclic voltammetry experiments revealed that 4.5c feature an irreversible, one-electron reduction wave by Epc = -1.90 V vs. SCE, while the 4.5a did not show evidence for reduction within the electrochemical window examined. The type of reduction wave for 4.5c was different to Ph-NOP (single quasi-reversible), Ph-BOP (single reversible reduction) and the

(2,4,6-Me3-C6H2)2-BBOP (two quasi-reversible). The reduction potential for 4.5c (Epc = -1.90

V) shifted negative by 120 mV to Ph-BOP, by 20 mV to Ph-NOP, and by 220 mV to the first reduction wave and by 110 mV to second reduction wave of (2,4,6-Me3-C6H2)2-BBOP. The comparison studies demonstrated that the reduction waves (Epc) of NBOPs occurred more readily than counterpart of BOPs, BBOPs and NOPs, which were attributed their lower π* orbital.

The investigation of R2-NBOP project revealed that, with extraordinary high quantum yield, small HOMO/LUMO gaps and great air stability, Ph2-NBOP is good candidate as building units. However, considering the low solubility in organic solvents, the structure should be modified by long side chains.

136

4.3 Experimental

General Procedures:

Experimental procedures were performed under nitrogen using either Schlenk line techniques or a Vacuum Atmospheres MBraun drybox. Tetrahydrofuran, toluene and diethyl ether were dried by distillation from sodium benzophenone ketyl. Hexanes was dried by distillation from sodium benzophenone in the presence of tetra(ethylene glycol)dimethyl ether. Methylene chloride was dried by distillation from calcium hydride. Methylene chloride

(99.99%, for spectroscopy) and methanol (200 proof) were degassed prior to use for UV-vis and fluorescence spectroscopy. All benzimidoyl chlorides were prepared using modified

19 1 31 1 procedures from the literature. NMR spectra ( H and P{ H}) were recorded in CDCl3, unless otherwise noted, on a Varian INOVA AS-400 spectrometer operating at 399.7 and

31 1 13 1 161.8 Hz, respectively. P{ H} NMR spectra were referenced to 85% H3PO4. C{ H} NMR spectra were recorded in CDCl3 on a Varian INOVA AS-600 spectrometer operating at 150.9

Hz, unless otherwise noted.

UV-vis and fluorescence spectra were recorded using a Cary-5G-UV-vis-NIR spectrophotometer and a Cary Eclipse spectrometer, respectively. Anthracene in ethanol was used as the quantum yield standard (conc. 5.0 × 10-6 M), and the calculation of quantum yield was measured as described.32 The excitation slit width for all measurements was kept at default settings (5 nm). Melting points were measured on a Thomas Hoover Capillary

Melting Point Apparatus. Elemental analyses were performed by Robertson Microlit

Laboratories, Ledgewood, New Jersey. High resolution mass spectrometry was performed by the University of Michigan Mass Spectrometry facility using a VG (Micromass) 70-250-S magnetic sector spectrometer with EI technique at 70 eV. 137

Tetraethyl(1,5-naphthylene)bis(phosphate) (4.2)

Triethylamine (26.3 g, 187 mmol) was added dropwise to a stirred mixture containing

1,5-dihydroxynaphthylene (4.1, 10.0 g, 62.4 mmol) and diethyl chlorophosphate (22.6 mL,

156 mmol) in 250 mL THF in a 500 mL round bottom flask. The solution was stirred for 12 h.

Aqueous HCl solution (100 mL, 1.2 M) and diethyl ether 250 mL was added, the mixture was stirred for ~15 min. The organic layer was separated and washed successively with degassed solutions of aqueous HCl (100 mL, 1.2 M), aqueous NaOH (250 mL, 1.0 M), distilled water

(200 mL) and was then dried over sodium sulfate. The solvent was removed by rotary

1 3 evaporation to yield a brown solid 4.2 (22.8 g, 84.4%); H NMR: δ 8.00 (d, 2H, JPH = 8.0

3 31 1 Hz), 7.54 (m, 2H), 7.47 (m, 2H), 4.26 (m, 8H), 1.35 (t, 12H, JHH = 7.2 Hz); P{ H} NMR: δ

13 1 -5.8 (s); C{ H} NMR (100 Hz): δ 146.5 (d, JPC = 6.9 Hz), 127.7 (d, JPC = 6.9 Hz), 125.9,

118.4, 115.6 (d, JPC = 2.3 Hz), 64.7 (d, JPC = 6.1 Hz), 16.0 (d, JPC = 6.6 Hz). ); mp: 73-74 ˚С; elemental analyses: calc. for C18H26O8P2 (M.W. 432.34), C 50.01%, H 6.06%; found: C

50.13%, H 6.01%.

Tetraethyl(1,5-dihydroxy-2,6-naphthylene)bis(phosphonate) ( 4.3 )

To a solution of diisopropylamide (37.6 mL, 266 mmol) in 100 mL THF, at -78 ˚С in a nitrogen atmosphere in a 500 mL round bottom flask, nBuLi (2.5 M in hexane, 102 mL, 266 mmol) was added. The mixture was stirred for 15 min to allow a white slurry lithium diisopropylamide (LDA) to form. Tetraethyl(1,5-naphthylene)bis(phosphate) (4.2, 23.0 g,

53.2 mmol) was dissolved in 100 mL THF, and then transferred to LDA by cannula, stirred for 1 h at -78 ˚С. The dry ice/acetone bath was removed, and solution was stirred additional 2 h at r. t. The mixture solution was poured over saturated ammonium chloride aqueous solution (250 mL), and then stirred until the precipitate was dissolved (~ 30 min). The 138 product was extract with methylene chloride 3 × 200 mL. The organic layer was separated and washed by distilled water, and dried over anhydrous sodium sulfate. The solvent was removed by rotary evaporation to yield a brown solid 4.3 (20.5 g, 89.0%) 1H NMR: δ 11.2 (s,

3 31 1 1H, OH), 7.87 (m, 1H), 7.36 (m, 1H), 4.11 (m, 4H), 1.33 (t, 6H, JHH = 7.2 Hz); P{ H}

13 1 NMR: δ 23.6 (s, 1P); C{ H} NMR (100 Hz): δ 160.1 (d, JPC = 7.6 Hz), 128.2 (dd, JPC =

13.2 Hz, JPC = 2.2 Hz), 125.7 (d, JPC = 6.3 Hz), 114.5 (d, JPC = 13.4 Hz), 103.9 (d, JPC =

178.4 Hz), 62.8 (d, JPC = 4.6 Hz), 16.2 (d, JPC = 6.6 Hz); mp: 141.0-141.5 ˚С; elemental analyses: calc. for C18H26O8P2 (M.W. 432.34), C 50.01%, H 6.06%; found: C 50.12%, H

6.02%.

2,6-diphosphino-1,5-naphthylenediol (4.4)

Tetraethyl(1,5-hydroxy-2,6-naphthylene)bis(phosphonate) (4.3, 10.0 g, 23.1 mmol) was added a solution of LiAlH4 (5.27 g, 139 mmol) in THF 150 mL in a 500 mL round bottom flask. The solution was stirred under nitrogen for 2 h, an aqueous solution of saturated ammonium chloride was added dropwise to quench the excess LiAlH4, and product was extracted with chloroform (300 mL). Organic layer was separated, and filtered through celite using glass fritted filter funnel. Solvents was removed by rotary evaporation to yield a white

1 3 3 solid 4.4 (2.41g, 95.6%); H NMR: δ 7.70 (d, 1H, JPH = 8.4 Hz), 7.52 (t, 1H, JPH = 8.4 Hz),

4 31 1 5.98 (d, 1H, OH, JPH = 4.0 Hz), 4.11 (s, 1H, PH), 3.58 (s, 1H, PH); P{ H} NMR: δ -156.3

13 1 (s, 1P). C{ H} NMR: δ 154.9 (d, JPC = 7.9 Hz), 133.2 (d, JPC = 19.3 Hz), 125.7 (d, JPC =

57.4 Hz), 114.2 (d, JPC = 7.7 Hz), 106.0 (d, JPC = 7.4 Hz); mp: 140-145 ˚С; elemental analyses: calc. for C10H10O2P2 (M.W. 224.13), C 53.59%, H 4.50%; found: C 53.86%, H

4.53%.

139

2,7-di-tert-butyl-naphtho[1,2-d:5,6-d’]bisoxaphosphole (4.5a)

2,6-diphosphino-1,5-naphthylenediol (4.4, 0.50 g, 2.2 mmol) and N-phenylpivalimidoyl chloride (2.6 g, 13 mmol) were dissolved into 20 mL THF in a 100 mL round bottom flask, the flask was outfitted with a reflux condenser and then refluxed under nitrogen for 16 h. The reaction mixture was filtered using glass fritted filter funnel. The solid was extracted with

THF (2 × 5 mL) and the combined filtrated was evaporated under vacuum yield a brown solid. Purification by column chromatography (CH2Cl2/ hexanes 1:1, Rf = 0.9) led to isolation

1 3 3 of a white solid 4.5a (0.21 g, 27%); H NMR: δ 8.24 (dd, 1H, JPH = 8.4 Hz, JHH = 2.0 Hz),

3 3 4 31 1 8.03 (dd, 1H, JPH = 8.4 Hz, JHH = 2.0 Hz), 1.56 (d, 9H, JHH = 1.2 Hz); P{ H} NMR: δ

13 1 81.8 (s); C{ H} NMR: δ 212.4 (d, JPC = 63.6 Hz), 156.3 (d, JPC = 3.2 Hz), 132.2 (d, JPC =

40.0 Hz), 126.0 (d, JPC = 14.4 Hz), 121.0 (d, JPC = 1.5 Hz), 116.0 (d, JPC = 9.1 Hz), 38.1 (d,

-6 -1 -1 JPC = 11.3 Hz), 30.1 (d, JPC = 8.6 Hz); UV (CH2Cl2, conc. 5 × 10 M): λmax, nm (ߝ, M cm )

-6 316 (24550); fluorescence (CH2Cl2, conc. 5 × 10 M): λF,max, nm (Int.) 386 (410); quantum yield (CH2Cl2): ΦF 0.07; mp: 208-212 ˚С; elemental analyses: calc. for C20H22O2P2 (M.W.

356.34), C 67.41%, H 6.22%; found: C 67.40%, H 6.21%.

2,7-di-adamantyl-naphtho[1,2-d:5,6-d’]bisoxaphosphole (4.5b)

2,6-diphosphino-1,5-naphthylenediol (4.4, 0.50 g, 2.2 mmol) and N- adamantylbenzimidoyl chloride (3.1 g, 11 mmol) were dissolved into 25 mL THF in a 100 mL round bottom flask, the flask was outfitted with a reflux condenser and then refluxed under nitrogen for 3 h. The reaction mixture was filtered using glass fritted filter funnel. The solid was extracted with THF (2 × 5 mL) and the combined filtrate was evaporated under vacuum to yield a brown solid. Purification by column chromatography (CH2Cl2/ hexanes 1:1,

140

1 3 Rf = 0.9) led to isolation of a white solid 4.5b (0.54 g, 47%); H NMR: δ 8.25 (dd, 1H, JPH =

3 3 3 8.4 Hz, JHH = 1.6 Hz), 8.04 (dd, 1H, JPH = 8.4 Hz, JHH = 2.0 Hz), 2.17 (m, 9H), 1.86 (s,

31 1 13 1 6H); P{ H} NMR: δ 80.5 (s); C{ H} NMR: δ 212.8 (d, JPC = 62.7 Hz), 156.1 (d, JPC = 3.0

Hz), 132.0 (d, JPC = 40.0 Hz), 126.1 (d, JPC = 21.0 Hz), 121.0, 116.1 (d, JPC = 9.2 Hz), 42.4

-6 (d, JPC = 8.9 Hz), 40.1 (d, JPC = 9.2 Hz), 36.7, 28.4; UV (CH2Cl2, conc. 5 × 10 M): λmax, nm

-1 -1 -6 (ߝ, M cm ) 318 (24336); fluorescence (CH2Cl2, conc. 5 × 10 M): λF,max, nm (Int.) 387

(461); quantum yield (CH2Cl2): ΦF 0.08; mp: 358-362 ˚С; elemental analyses: calc. for

C32H34O2P2 (M.W. 512.56), C 74.99%, H 6.69%; found: C 74.00%, H 6.63%.

2,7-di-phenyl-naphtho[1,2-d:5,6-d’]bisoxaphosphole (4.5c)

2,6-diphosphino-1,5-naphthylenediol (4.4, 1.0 g, 4.5 mmol) and N-phenylbenzimidoyl chloride (4.8 g, 22 mmol) were dissolved into 50 mL THF in a 250 mL round bottom flask, the flask was outfitted with a reflux condenser and then refluxed under nitrogen for 21 h. The reaction mixture was filtered using glass fritted filter funnel. The residue solid was collected and purified by flash column chromatography (CH2Cl2/ hexanes 1:4) led to isolation of a

1 3 3 yellow solid 4.5c (0.19 g, 11%); H NMR: δ 8.40 (d, 1H, JPH = 8.4 Hz), 8.15 (d, 3H, JPH =

31 1 -6 8.0), 7.52 - 7.43 (m, 3H); P{ H} NMR: δ 80.5 (s); UV (CH2Cl2, conc. 5 × 10 M): λmax, nm

-1 -1 -7 (ߝ, M cm ) 387 (44834); fluorescence (CH2Cl2, conc. 5 × 10 M): λF,max, nm (Int.) 422

(960); quantum yield (CH2Cl2): ΦF 0.63; mp: 265-270 ˚С; HRMS m/z: 396.0478 (calc.

396.0469).

141

Crystallographic studies of NBOP

A summary of crystal data and collection parameters for crystal structure of 4.4, 4.5a and 4.5c is provided in Table 4.11, and detailed descriptions of data collection as well as data solution are provided below. Compound 4.5a was analyzed at the Department of Chemistry,

Case Western Reserve University, Cleveland, OH 44106, and compounds 4.4 and 4.5c were done at the Department of Chemistry and Biochemistry, University of California, San Diego,

La Jolla, CA 92093. Thermal ellipsoid diagrams were generated with Mercury 2.3 software package. The crystals were transferred to a Bruker AXS APEX II diffractometer with a CCD area detector (4.4 and 4.5a) or Bruker SMART 6000 (4.5c), and centered in the X-ray beam, and cooled using a nitrogen-flow low-temperature apparatus that had been precisely calibrated by a thermocouple placed at the same position as the crystal. Compound 4.4 and

4.5a, X-ray quality crystals were grown in diethyl ether and grown at room temperature by slow evaporation. Compound 4.5c, X-ray quality crystals were dissolved in CH2Cl2 and grown at room temperature by slow evaporation.

Table 4.10 Crystal data and collection parameters of 4.4, 4.5a and 4.5c

4.4 4.5a 4.5c

formula C10H10O2P2 C20H22O2P2 C24H14O2P2

fw 224.12 356.32 396.29

space group P2(1)/c P2(1)/c P2(1)/n

temperature (K) 123 160 100

a (Å) 4.6031(5) 10.5582(7) 3.9088(2)

b (Å) 8.0600(9) 10.0690(7) 19.9940(10)

142

c (Å) 13.9923(15) 9.5461(7) 11.2543(5)

α (deg) 86.660(4) 90.00 90.00

β (deg) 89.391(4) 112.5050(10) 93.829(3)

γ (deg) 74.183(4) 90.00 90.00

V (Å3) 498.62(9) 937.57(11) 877.59(7)

Z 2 2 2

densitycalc 1.493 1.241 1.500

(g/cm3)

radiation Mo Kα (λ = 0.71073 Mo Kα (λ = 0.71073 Cu Kα (λ = 1.54178

Å) Å) Å)

monochromator graphite graphite multilayer mirror

optics

detector CCD area detector CCD area detector Bruker SMART 6000

no. of reflns hemisphere hemisphere hemisphere

measd

2 θ range (deg) 5.26-50.88 5.82-55.96 8.84-136.52

cryst dimens 0.33 × 0.10 × 0.06 0.44 × 0.14 × 0.12 0.08 × 0.03 × 0.02

(mm)

no. of reflns 4685 10394 10573

measd

no. of unique 1744 2115 1564

reflns

no. of 1744 2115 1564

143

observations

no. of params 147 112 127

R, Rw, Rall 0.0421, 0.1214, 0.0305, 0.0885, 0.0622, 0.1625,

0.0472 0.0349 0.0752

GOF 1.070 1.077 1.046

Electrochemical Studies of NBOPs

Cyclic voltammetry experiments were performed in a nitrogen- filled MBraun drybox outfitted with a CH Instrument workstation (CHI630C) at room temperature.

n Tetrabutylammonium tetrafluoroborate, [ Bu4N][BF4], was recrystallized five times using ethyl acetate and ether, dried thoroughly under vacuum, and stored in the drybox. Ferrocene was purified by sublimation under vacuum and stored in the drybox. All glassware was oven- dried overnight before use. A glassy carbon working electrode was polished with 0.05μm alumina and thoroughly cleaned and dried before use. A silver wire was utilized as a quasi- reference electrode, and a platinum wire was the counter electrode. All scans were performed at a scan rate of 0.1 V/s unless otherwise stated. All spectra were referenced to SCE using ferrocene as an internal standard.

Solutions with a concentration of 0.001M NOPs in THF were used for reduction analyses. A three-electrode system, with glassy carbon as the working electrode, silver wire as the quasi-reference electrode, and platinum wire as the counter electrode, was utilized. All

n scans were performed with 0.1 M tetrabutylammonium tetrafluoroborate, [ Bu4N] [BF4], in

THF as the supporting electrolyte, with a scan rate of 0.1 V/s. Ferrocene was utilized as an

144 internal reference because of the use of a quasi-reference electrode during analyses.

Ferrocene (final concentration 0.001 M) was added after the initial scans of compounds. The reduction potentials were thus referenced to the ferrocene/ferrocenium redox couple versus saturated calomel electrode (E1/2 = 0.55 V vs SCE). Reversibility was ascertained by scanning compounds 4.5c at various scan rates (25-200 mV) and generating linear plots of scan rates versus Ep for both ferrocene.

0.8

0.7

0.6 Reduction Oxidation

0.5 Current (A) Current

0.4

0.3 468101214 Scan Rate1/2 (V1/2 in mV/s)

Figure 4.28 Scan rate vs. Ep plot of ferrocene redox couple

145

0.00002

0.00001 Increasing Scan Rate

0.00000

25mV/s -0.00001 50mV/s Current (A) 75mV/s 100mV/s + -0.00002 Fc/Fc 125mV/s 150mV/s 175mV/s -0.00003 200mV/s

1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -2.5 Potential vs. SCE (V)

Figure 4.29 Variable scan rate voltammogram for compound 4.5c

(Scan rates of 25 to 200 mV/s, conc. is 0.001 M in THF)

146

4.4 works Cited

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(23) Laughlina, F. L.; Rheingoldb, A. L.; Deligonula, N.; Golenb, J. A.;

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149

Chapter 5: Conclusions

Oxaphosphole (OP) is a five membered heterocyclic ring, containing a P=C bond. By fusing on an aromatic ring such as benzene or naphthalene, OP compounds increase the conjugation of molecules. With their coplanar figuration, OP compounds, such as BBOPs,

NOPs and NBOPs could be anticipated as candidates of building units to synthesize π- conjugated polymer materials.

In order to extend the investigations of conjugated materials with P=C bonds, work on the design, synthesis and characterization of new OP compounds has been undertaken. In this effort, three series of new fluorescent π-conjugated materials, R2-BBOP, R-NOP and R2-

NBOP have been successfully synthesized and characterized by multinuclear NMR, UV-vis and fluorescence spectroscopy, elemental analysis or HRMS. Some of model compounds were characterized by cyclic voltammetry experiments and single-crystal X-ray diffraction experiments.

Figure 5.1 Structure and substituents of BBOP, NOP and NBOP

The study of R2-BBOP (2.28) included the synthesis and characterization of two new

t conjugated materials containing alkyl substituents. The single-crystal structure of Bu2-BBOP 150

(2.28a) proved a coplanar structure with torsion angle 178.7˚, which ideally maximized the conjugation across the whole conjugated back bone. The P=C bond length of 1.694(1) Å is longer than that found in most phosphaalkenes and shorter than the P-C single bond.

2.28 exhibited better photoluminescence than R-BOPs, which had absorption maxima around 305 nm and emission maxima around 370 nm. This is attributed to the extension of

BBOP’s conjugated length by fusing two oxaphospholes, which decreased the

HOMO/LUMO band gaps and consequently increased the conjugation compared to the BOPs.

The quantum yields of 2.28 was low (a, F = 0.04; b, F = 0.03), due to the alkyl substituents, which is the same as the alkyl substituted Ad-BOP (F = 0.04).

Cyclic voltammetry experiments revealed that 2.28a and b features a single, reversible, one-electron reduction wave near E1/2 = -2.35 V vs. SCE, whereas in the BOP counterpart no reduction wave was observed. It should explained by the heterocyclic ring of BBOPs increased species conjugation, and lower π* orbital (reductive potential), consequently easing the reduction process of BBOPs.

The study of R-NOP (3.3) included the synthesis and characterization of seven new conjugated materials (3.3a-g), two of which contain alkyl substituents (3.3a,b) and five contain aryl substituents (3.3c-g). 3-phosphino-2-naphthol (3.13) exhibits greater air-stability than most primary phosphine. 3.3 also possessed reasonable air and water stability, especially in the solid state. Single-crystal structures of Ad-NOP (3.3b) and MeC6H4-NOP (3.3d) both display coplanar conformation in the heterocyclo ring. Containing aryl substituent, 3.3d exhibits a good coplanar figuration with torsion angle around 175˚. Furthermore, single crystals of 3.3d packed in herringbone geometry.

151

The studies of PL displayed that alkyl- and aryl- substituted NOPs exhibited absorption maxima at 333 nm and around 355 nm, respectively, while they displayed emission maxima

~383 nm and ~465 nm, respectively. This illustrate that the aryl-NOPs possess smaller

HOMO/LUMO band gaps than alkyl-NOPs, which was confirmed by DFT calculations.

Compared to BOPs (λmax ~ 305 nm and λF,max ~ 370 nm.), 3.3 had observed red shift in both absorption and emission maxima. It demonstrated that NOPs performed smaller

HOMO/LUMO band gaps than counterparts of BOPs, which was also confirmed by DFT calculations.

Cyclic voltammetry experiments revealed that alkyl-NOPs (3.3a and 3.3b) did not show evidence of reduction within the electrochemical window examined. By contrast, aryl substituted R-NOPs 3.3c, 3.3d and 3.3g showed quasi-reversible reduction waves (ipa/ipc ~

0.6) between -1.8 to -1.9 vs. SCE. The initial reduction waves (Epc) of NOPs occurred more readily than counterparts of BOPs, which can be attributed the NOPs’ lower π* orbital.

The studies of R2-NBOP (4.5) included the synthesis and characterization of three new conjugated materials (3.3a-c), two of which contain alkyl substituents (3.3a,b) and one contains aryl substituents (3.3c). The white solid diprimary phosphine 2,6-diphosphino-1,5- naphthylenediol (4.4) displayed even greater air-stability than 3-phosphino-2-naphthol (3.13).

And 4.5 possessed great air and water stability even in organic solvent for weeks. Single-

t crystal structures of Bu2-NBOP (4.5a) and Ph2-NBOP (4.5c) both display coplanar conformation for the heterocyclic ring. Containing phenyl substituent, 4.5c exhibits a good coplanar figuration with a torsion angle of about 177˚. Furthermore, single crystals of 4.5a and c both packed in herringbone geometry.

The studies of PL revealed that alkyl- and aryl- substituted NBOPs exhibited blue fluorescent color. The absorption spectra displayed one absorption peak for the alkyl-NBOP, 152

4.5a and 4.5b, featuring the π-π* transition at 316 nm and 318 nm. In contrast, aryl-NOPs

(4.5c) showed two peaks at 372 nm and 387 nm with doubled intensity. A red shift of absorption maxima was also observed between alkyl and aryl substituted NBOPs, however the value is significant (~70 nm) compared to BBOPs (~30 nm) or NOPs (~20 nm). It illustrated that the aryl-NBOPs possess much smaller HOMO/LUMO band gaps than alkyl-

NBOPs. Fluorescence emission spectra depicted that 4.5a and b exhibited three emission peaks around 352nm, 369nm and 387nm, respectively. In contrast, 4.5c displayed only one broad peak at 422 nm with quite high intensity. A 30nm red shift of emission maximum for

4.5c versus 4.5a and b was also observed. It is noteworthy that the quantum yield of 4.5c (ΦF

= 0.63) is about 8 times higher than other two alkyl substituted compounds (4.5a, ΦF = 0.07;

4.5b, ΦF = 0.08).

Cyclic voltammetry experiments revealed that 4.5c features a single, irreversible, one- electron reduction wave by Epc = -1.90 V vs SCE, while 4.5a did not show evidence for reduction within the electrochemical window examined. The type of reduction wave for 4.5c was different than Ph-NOP (single quasi-reversible), Ph-BOP (single reversible reduction) and the (2,4,6-Me3-C6H2)2-BBOP (two quasi-reversible). The reduction potential for 4.5c (Epc

= -1.90 V) shifted negatively by 120 mV to Ph-BOP, by 20 mV to Ph-NOP, and by220 mV to the first reduction wave and by 110 mV to second reduction wave of (2,4,6-Me3-C6H2)2-

BBOP. The comparison studies demonstrate that the reduction waves (Epc) of NBOP occurred more readily than the counterpart of BOPs, BBOPs and NOPs which can be attributed its lower π* orbital.

The investigation of 4.5 revealed that, with an extraordinary high quantum yield, small

HOMO/LUMO band gaps and great air stability, 4.5c was also good candidate a building unit.

153

However, considering the low solubility in organic solvents, the structure should be modified by long side chains.

In summary, these π-conjugated materials containing OPs exhibited a coplanar structure on the heterocyclic ring with aryl substituents and possessed great conjugation. They possess significant photoluminescence properties, electrochemical properties and have the potential applications for use in photo- or electro- devises such as OLEDs or OFETs.

154

Appendix A: Crystal Structure determination and Data

Table A.1 Crystal structure determination for 2.28a.

t Bu2-BBOP

formula C16 H20 O2 P2

fw 306.26

space group P2(1)/n

temperature (K) 100(2)

a (Å) 5.4948(5)

b (Å) 7.2202(7)

c (Å) 19.2488(18)

α (deg) 90.00

β (deg) 91.3450(10)

γ (deg) 90.00

V (Å3) 763.46(12)

Z 2

3 densitycalc (g/cm ) 1.332

radiation MoK\a (λ = 0.71073 Å)

monochromator graphite

detector CCD area detector

no. of reflns measd hemisphere

2 θ range (deg) 6.02 – 55.7

cryst dimens (mm) 0.51x 0.46x 0.25

155 no. of reflns measd 8676 no. of unique reflns 7145 no. of observations 7145 no. of params 94

R, Rw, Rall 0.0291, 0.0864, 0.0298

GOF 1.132

156

2.28a: 2,6-Di-tert-butyl-benzo[1,2-d:4,5-d’]bisoxaphosphole

Table A.2 Atomic coordinates (x 10^4) and equivalent isotropic displacement parameters (A^2 x

10^3) for 2.28a. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor.

______

x y z U(eq)

______

P(1) 4065(1) 4997(1) 1187(1) 14(1)

O(1) 2187(1) 7958(1) 613(1) 13(1)

C(5) 5074(2) 8836(1) 1509(1) 12(1)

C(1) 3809(2) 7325(1) 1106(1) 12(1)

C(2) 1040(2) 6512(2) 284(1) 12(1)

C(6) 6843(2) 7968(2) 2033(1) 18(1)

C(3) 1779(2) 4765(2) 521(1) 12(1)

C(4) -702(2) 6806(2) -228(1) 13(1)

157

C(7) 6452(2) 10095(1) 1016(1) 16(1)

C(8) 3180(2) 9971(1) 1892(1) 17(1)

______

Table A.3 Bond lengths (Å) and bond angles (˚) for 2.28a

______

P(1)-C(1) 1.6940(11)

P(1)-C(3) 1.7817(12)

O(1)-C(1) 1.3645(13)

O(1)-C(2) 1.3672(12)

C(5)-C(1) 1.4999(14)

C(5)-C(6) 1.5208(14)

C(5)-C(7) 1.5275(14)

C(5)-C(8) 1.5281(14)

C(2)-C(4) 1.3744(15)

C(2)-C(3) 1.3981(14)

C(6)-H(6A) 0.9800

C(6)-H(6B) 0.9800

C(6)-H(6C) 0.9800

C(3)-C(4)#1 1.3920(14)

C(4)-C(3)#1 1.3920(14)

C(4)-H(4) 0.9500

C(7)-H(7A) 0.9800

158

C(7)-H(7B) 0.9800

C(7)-H(7C) 0.9800

C(8)-H(8A) 0.9800

C(8)-H(8B) 0.9800

C(8)-H(8C) 0.9800

C(1)-P(1)-C(3) 88.34(5)

C(1)-O(1)-C(2) 110.64(8)

C(1)-C(5)-C(6) 108.98(8)

C(1)-C(5)-C(7) 110.00(9)

C(6)-C(5)-C(7) 109.83(9)

C(1)-C(5)-C(8) 109.10(9)

C(6)-C(5)-C(8) 109.38(9)

C(7)-C(5)-C(8) 109.52(9)

O(1)-C(1)-C(5) 113.78(9)

O(1)-C(1)-P(1) 116.62(7)

C(5)-C(1)-P(1) 129.59(8)

O(1)-C(2)-C(4) 121.32(9)

O(1)-C(2)-C(3) 114.27(9)

C(4)-C(2)-C(3) 124.41(9)

C(5)-C(6)-H(6A) 109.5

C(5)-C(6)-H(6B) 109.5

H(6A)-C(6)-H(6B) 109.5

C(5)-C(6)-H(6C) 109.5

159

H(6A)-C(6)-H(6C) 109.5

H(6B)-C(6)-H(6C) 109.5

C(4)#1-C(3)-C(2) 119.06(10)

C(4)#1-C(3)-P(1) 130.82(8)

C(2)-C(3)-P(1) 110.12(8)

C(2)-C(4)-C(3)#1 116.54(9)

C(2)-C(4)-H(4) 121.7

C(3)#1-C(4)-H(4) 121.7

C(5)-C(7)-H(7A) 109.5

C(5)-C(7)-H(7B) 109.5

H(7A)-C(7)-H(7B) 109.5

C(5)-C(7)-H(7C) 109.5

H(7A)-C(7)-H(7C) 109.5

H(7B)-C(7)-H(7C) 109.5

C(5)-C(8)-H(8A) 109.5

C(5)-C(8)-H(8B) 109.5

H(8A)-C(8)-H(8B) 109.5

C(5)-C(8)-H(8C) 109.5

H(8A)-C(8)-H(8C) 109.5

H(8B)-C(8)-H(8C) 109.5

______

160

Table A.4 Anisotropic displacement parameters (A^2 x 10^3) for 2.28a. The anisotropic displacement factor exponent takes the form:

-2 pi^2 [ h^2 a*^2 U11 + ... + 2 h k a* b* U12 ]

______

U11 U22 U33 U23 U13 U12

______

P(1) 17(1) 10(1) 15(1) 0(1) -6(1) 0(1)

O(1) 15(1) 10(1) 13(1) -1(1) -5(1) -1(1)

C(5) 13(1) 11(1) 13(1) -1(1) -3(1) -1(1)

C(1) 12(1) 13(1) 11(1) 0(1) -2(1) 0(1)

C(2) 14(1) 10(1) 12(1) -2(1) -1(1) -2(1)

C(6) 20(1) 15(1) 20(1) 1(1) -10(1) -2(1)

C(3) 14(1) 12(1) 11(1) 0(1) -2(1) 0(1)

C(4) 16(1) 11(1) 13(1) 1(1) -3(1) 0(1)

C(7) 15(1) 14(1) 18(1) -1(1) 1(1) -2(1)

C(8) 16(1) 18(1) 16(1) -5(1) 1(1) -1(1)

______

161

Table A.5 Hydrogen coordinates (x 10^4) and isotropic displacement parameters (A^2 x 10^3) for 2.28a.

______

x y z U(eq)

______

H(6A) 5950 7156 2346 28

H(6B) 7658 8946 2304 28

H(6C) 8061 7242 1788 28

H(4) -1147 8018 -375 16

H(7A) 7723 9380 788 24

H(7B) 7201 11115 1280 24

H(7C) 5318 10597 663 24

H(8A) 2005 10495 1556 25

H(8B) 3993 10976 2149 25

H(8C) 2328 9169 2218 25

______

162

Table A.6 Crystal structure determination for 3.12, 3.3b and 3.3d.

3.12 3.3b 3.3d formula C14 H12 O4 P C21 H21 O P C18 H13 O P fw 275.21 320.35 276.25 space group P2(1)/c P2(1)2(1)2(1) P2(1) temperature (K) 170 100 100 a (Å) 9.6672(1) 6.5436(1) 11.755(1) b (Å) 11.5278(2) 13.3825(1) 7.3511(2) c (Å) 12.8735(2) 18.4075(2) 16.433(1)

α (deg) 90.00 90.00 90.00

β (deg) 102.6630(10) 90.00 108.790(3)

γ (deg) 90.00 90.00 90.00

V (Å3) 1399.7(2) 1611.94(2) 1344.3(4)

Z 4 4 4 densitycalc 1.306 1.320 1.365

(g/cm3) radiation MoK\a (λ = 0.71073 Å) MoK\a (λ = 0.71073 Å) MoK\a (λ =

0.71073 Å) monochromator graphite graphite graphite detector CCD area detector CCD area detector CCD area detector no. of reflns hemisphere hemisphere hemisphere measd

163

2 θ range (deg) 4.8-55.9 6.60-50.74 5.24-61.4 cryst dimens 0.42 x 0.29 x 0.10 0.26 x 0.25 x 0.20 0.29 x 0.24 x 0.08

(mm) no. of reflns 16803 4287 10573 measd no. of unique 3362 2336 6734 reflns no. of 3362 2336 6734 observations no. of params 177 209 363

R, Rw, Rall 0.0513, 0.1702, 0.0551 0.0425, 0.1110, 0.0462 0.0528, 0.1239,

0.0772

GOF 1.132 1.070 1.012

164

3.12: Diethyl(3-hydroxy-2-naphthyl)phosphonate

Table A.7 Atomic coordinates ( x 10^4) and equivalent isotropic displacement parameters (A^2 x 10^3) for 3.12. U (eq) is defined as one third of the trace of the orthogonalized Uij tensor.

______

x y z U(eq)

______

P(1) 5538(1) 6890(1) 2130(1) 34(1)

C(1) 4032(2) 7579(2) 1315(1) 32(1)

C(2) 2750(2) 7448(2) 1600(1) 34(1)

C(3) 1478(2) 7858(2) 945(1) 33(1)

C(8) 1542(2) 8420(2) -23(1) 32(1)

C(10) 4095(2) 8185(2) 361(2) 35(1)

C(6) -1019(2) 8615(2) -413(2) 43(1)

165

C(7) 248(2) 8790(2) -697(2) 38(1)

C(5) -1075(2) 8073(2) 554(2) 47(1)

C(9) 2875(2) 8601(2) -283(2) 36(1)

C(4) 145(2) 7702(2) 1222(2) 43(1)

C(11) 7199(3) 5222(3) 1780(3) 73(1)

C(12) 7153(11) 4290(9) 1002(11) 80(2)

O(1) 5187(2) 6344(1) 3076(1) 45(1)

O(2) 6029(2) 6013(1) 1357(1) 47(1)

C(13) 6808(3) 8745(2) 3076(2) 54(1)

C(14) 8244(3) 9295(2) 3267(2) 63(1)

O(4) 5391(1) 8308(2) 136(1) 48(1)

C(12A) 7675(11) 4620(9) 949(11) 80(2)

O(3) 6822(1) 7752(1) 2392(1) 41(1)

______

166

Table A.8 Bond lengths [A] and angles [deg] for 3.12.

______

P(1)-O(1) 1.4750(14)

P(1)-O(2) 1.5641(15)

P(1)-O(3) 1.5674(15)

P(1)-C(1) 1.7835(17)

C(1)-C(2) 1.376(2)

C(1)-C(10) 1.426(3)

C(2)-C(3) 1.411(2)

C(2)-H(2) 0.9500

C(3)-C(8) 1.418(3)

C(3)-C(4) 1.421(2)

C(8)-C(9) 1.416(2)

C(8)-C(7) 1.422(2)

C(10)-O(4) 1.354(2)

C(10)-C(9) 1.370(3)

C(6)-C(7) 1.368(3)

C(6)-C(5) 1.405(3)

C(6)-H(6) 0.9500

C(7)-H(7) 0.9500

C(5)-C(4) 1.367(3)

167

C(5)-H(5) 0.9500

C(9)-H(9) 0.9500

C(4)-H(4) 0.9500

C(11)-C(12A) 1.433(12)

C(11)-O(2) 1.462(3)

C(11)-C(12) 1.463(12)

C(12)-C(12A) 0.648(11)

C(13)-O(3) 1.447(3)

C(13)-C(14) 1.497(3)

C(13)-H(13A) 0.9900

C(13)-H(13B) 0.9900

C(14)-H(14A) 0.9800

C(14)-H(14B) 0.9800

C(14)-H(14C) 0.9800

O(4)-H(4A) 0.8400

O(1)-P(1)-O(2) 113.98(9)

O(1)-P(1)-O(3) 114.07(8)

O(2)-P(1)-O(3) 102.14(8)

O(1)-P(1)-C(1) 111.69(8)

O(2)-P(1)-C(1) 103.63(8)

O(3)-P(1)-C(1) 110.49(8)

C(2)-C(1)-C(10) 119.58(16)

C(2)-C(1)-P(1) 117.50(14)

168

C(10)-C(1)-P(1) 122.80(13)

C(1)-C(2)-C(3) 121.51(17)

C(1)-C(2)-H(2) 119.2

C(3)-C(2)-H(2) 119.2

C(2)-C(3)-C(8) 118.53(15)

C(2)-C(3)-C(4) 121.82(18)

C(8)-C(3)-C(4) 119.64(17)

C(9)-C(8)-C(3) 119.47(16)

C(9)-C(8)-C(7) 122.41(17)

C(3)-C(8)-C(7) 118.11(16)

O(4)-C(10)-C(9) 123.23(17)

O(4)-C(10)-C(1) 116.83(16)

C(9)-C(10)-C(1) 119.94(16)

C(7)-C(6)-C(5) 120.91(18)

C(7)-C(6)-H(6) 119.5

C(5)-C(6)-H(6) 119.5

C(6)-C(7)-C(8) 120.78(19)

C(6)-C(7)-H(7) 119.6

C(8)-C(7)-H(7) 119.6

C(4)-C(5)-C(6) 120.04(18)

C(4)-C(5)-H(5) 120.0

C(6)-C(5)-H(5) 120.0

C(10)-C(9)-C(8) 120.85(17)

169

C(10)-C(9)-H(9) 119.6

C(8)-C(9)-H(9) 119.6

C(5)-C(4)-C(3) 120.5(2)

C(5)-C(4)-H(4) 119.7

C(3)-C(4)-H(4) 119.7

C(12A)-C(11)-O(2) 111.9(6)

C(12A)-C(11)-C(12) 25.8(4)

O(2)-C(11)-C(12) 107.3(6)

C(12A)-C(12)-C(11) 74.4(19)

C(11)-O(2)-P(1) 118.91(16)

O(3)-C(13)-C(14) 107.6(2)

O(3)-C(13)-H(13A) 110.2

C(14)-C(13)-H(13A) 110.2

O(3)-C(13)-H(13B) 110.2

C(14)-C(13)-H(13B) 110.2

H(13A)-C(13)-H(13B) 108.5

C(13)-C(14)-H(14A) 109.5

C(13)-C(14)-H(14B) 109.5

H(14A)-C(14)-H(14B) 109.5

C(13)-C(14)-H(14C) 109.5

H(14A)-C(14)-H(14C) 109.5

H(14B)-C(14)-H(14C) 109.5

C(10)-O(4)-H(4A) 109.5

170

C(12)-C(12A)-C(11) 79.7(19)

C(13)-O(3)-P(1) 121.33(13)

______

171

Table A.9 Anisotropic displacement parameters (A^2 x 10^3) for 3.12. The anisotropic displacement factor exponent takes the form:

-2 pi^2 [ h^2 a*^2 U11 + ... + 2 h k a* b* U12 ]

______

U11 U22 U33 U23 U13 U12

______

P(1) 26(1) 46(1) 31(1) 2(1) 5(1) 5(1)

C(1) 23(1) 42(1) 30(1) 0(1) 5(1) 3(1)

C(2) 27(1) 42(1) 33(1) 0(1) 8(1) 0(1)

C(3) 24(1) 40(1) 36(1) -4(1) 7(1) -1(1)

C(8) 25(1) 37(1) 34(1) -6(1) 4(1) 1(1)

C(10) 24(1) 48(1) 33(1) 2(1) 9(1) 1(1)

C(6) 25(1) 53(1) 48(1) -11(1) -2(1) 2(1)

C(7) 29(1) 46(1) 38(1) -5(1) 1(1) 3(1)

C(5) 23(1) 63(1) 55(1) -9(1) 10(1) -3(1)

C(9) 29(1) 46(1) 33(1) 4(1) 7(1) 2(1)

C(4) 28(1) 57(1) 46(1) -1(1) 12(1) -3(1)

C(11) 70(2) 75(2) 73(2) -1(1) 13(1) 36(2)

C(12) 85(6) 69(5) 95(3) -10(4) 40(5) 23(4)

O(1) 37(1) 62(1) 35(1) 9(1) 7(1) 3(1)

O(2) 44(1) 54(1) 42(1) -4(1) 6(1) 14(1)

C(13) 47(1) 49(1) 68(2) -10(1) 14(1) 2(1)

C(14) 64(2) 52(1) 73(2) -3(1) 13(1) -15(1)

172

O(4) 24(1) 83(1) 40(1) 15(1) 11(1) 6(1)

C(12A) 85(6) 69(5) 95(3) -10(4) 40(5) 23(4)

O(3) 27(1) 54(1) 42(1) -2(1) 5(1) 2(1)

______

173

Table A.10 Hydrogen coordinates (x 10^4) and isotropic displacement parameters (A^2 x 10^3) for 3.12.

______

x y z U(eq)

______

H(2) 2720 7073 2251 40

H(6) -1872 8863 -876 52

H(7) 264 9163 -1352 46

H(5) -1962 7965 745 56

H(9) 2925 9017 -911 43

H(4) 102 7338 1876 51

H(13A) 6593 8498 3760 65

H(13B) 6074 9306 2732 65

H(14A) 8960 8738 3620 95

H(14B) 8262 9981 3720 95

H(14C) 8451 9528 2584 95

H(4A) 5301 8403 -523 72

______

174

3.3b: 2(adamantyl)naphtho(2,3-d)oxaphosphole

Table A.11 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (Å2x

103) for 3.3b. U (eq) is defined as one third of the trace of the orthogonalized Uij tensor.

______

x y z U(eq)

______

P(1) 11773(1) 7478(1) 784(1) 23(1)

O(1) 8200(3) 8092(1) 1272(1) 22(1)

C(1) 12035(5) 11467(2) 998(2) 31(1)

C(2) 10053(4) 11190(2) 1388(1) 25(1)

C(3) 10009(5) 10064(2) 1526(1) 23(1)

C(4) 10082(4) 9486(2) 800(1) 18(1)

175

C(5) 10011(4) 8386(2) 944(1) 20(1)

C(6) 10038(4) 6593(2) 1193(1) 20(1)

C(7) 10185(4) 5574(2) 1320(1) 21(1)

C(8) 8553(5) 5051(2) 1655(1) 22(1)

C(9) 8664(5) 4006(2) 1799(1) 25(1)

C(10) 7094(5) 3514(2) 2133(1) 28(1)

C(11) 5309(5) 4036(2) 2340(1) 27(1)

C(12) 5144(5) 5037(2) 2210(1) 25(1)

C(13) 6752(4) 5576(2) 1865(1) 21(1)

C(14) 6601(5) 6615(2) 1732(1) 24(1)

C(15) 8222(5) 7084(2) 1412(1) 21(1)

C(16) 8228(5) 11494(2) 917(1) 25(1)

C(17) 8309(5) 10939(2) 191(1) 25(1)

C(18) 8251(5) 9808(2) 324(1) 26(1)

C(19) 10299(5) 11214(2) -199(1) 30(1)

C(20) 12126(4) 10906(2) 269(2) 29(1)

C(21) 12073(4) 9767(2) 404(2) 28(1)

______

176

Table A.12 Bond lengths [Å] and angles [°] for 3.3b.

______

P(1)-C(5) 1.700(3) C(7)-C(8) 1.417(4)

P(1)-C(6) 1.806(3) C(8)-C(13) 1.426(4)

O(1)-C(15) 1.373(3) C(8)-C(9) 1.426(4)

O(1)-C(5) 1.386(3) C(9)-C(10) 1.367(4)

C(1)-C(2) 1.527(4) C(10)-C(11) 1.413(4)

C(1)-C(20) 1.539(4) C(11)-C(12) 1.366(4)

C(2)-C(3) 1.529(4) C(12)-C(13) 1.425(4)

C(2)-C(16) 1.530(4) C(13)-C(14) 1.415(4)

C(3)-C(4) 1.544(3) C(14)-C(15) 1.366(4)

C(4)-C(5) 1.497(4) C(16)-C(17) 1.531(4)

C(4)-C(21) 1.540(4) C(17)-C(19) 1.532(4)

C(4)-C(18) 1.546(4) C(17)-C(18) 1.534(4)

C(6)-C(7) 1.387(4) C(19)-C(20) 1.530(4)

C(6)-C(15) 1.416(4) C(20)-C(21) 1.545(4)

C(5)-P(1)-C(6) 88.29(12) C(2)-C(3)-C(4) 110.43(19)

C(15)-O(1)-C(5) 110.6(2) C(5)-C(4)-C(21) 110.5(2)

C(2)-C(1)-C(20) 108.9(2) C(5)-C(4)-C(3) 109.81(19)

C(1)-C(2)-C(3) 109.5(2) C(21)-C(4)-C(3) 108.3(2)

C(1)-C(2)-C(16) 109.5(2) C(5)-C(4)-C(18) 110.5(2)

C(3)-C(2)-C(16) 110.0(2) C(21)-C(4)-C(18) 108.6(2)

177

C(3)-C(4)-C(18) 109.1(2) C(16)-C(17)-C(19) 108.8(2)

O(1)-C(5)-C(4) 112.5(2) C(16)-C(17)-C(18) 109.7(2)

O(1)-C(5)-P(1) 116.91(18) C(19)-C(17)-C(18) 109.4(2)

C(4)-C(5)-P(1) 130.6(2) C(17)-C(18)-C(4) 110.3(2)

C(7)-C(6)-C(15) 117.8(3) C(20)-C(19)-C(17) 109.6(2)

C(7)-C(6)-P(1) 132.2(2) C(19)-C(20)-C(1) 109.2(2)

C(15)-C(6)-P(1) 109.95(19) C(19)-C(20)-C(21) 109.8(3)

C(6)-C(7)-C(8) 120.4(3) C(1)-C(20)-C(21) 109.8(2)

C(7)-C(8)-C(13) 119.9(2) C(4)-C(21)-C(20) 109.6(2)

C(7)-C(8)-C(9) 121.8(3)

C(13)-C(8)-C(9) 118.4(3)

C(10)-C(9)-C(8) 121.2(3)

C(9)-C(10)-C(11) 120.3(3)

C(12)-C(11)-C(10) 120.2(3)

C(11)-C(12)-C(13) 121.1(3)

C(14)-C(13)-C(12) 121.5(3)

C(14)-C(13)-C(8) 119.6(3)

C(12)-C(13)-C(8) 118.8(3)

C(15)-C(14)-C(13) 118.2(3)

C(14)-C(15)-O(1) 121.6(3)

C(14)-C(15)-C(6) 124.1(3)

O(1)-C(15)-C(6) 114.3(3)

C(2)-C(16)-C(17) 109.8(2)

178

______

Table A.13 Anisotropic displacement parameters (Å2x 103) for 3.3b. The anisotropic displacement factor exponent takes the form: -2 2[ h2 a*2U11 + ... + 2 h k a* b* U12]

______

U11 U22 U33 U23 U13 U12

______

P(1) 26(1) 18(1) 26(1) 2(1) 4(1) 3(1)

O(1) 25(1) 18(1) 25(1) 1(1) 2(1) 0(1)

C(1) 29(2) 18(1) 45(2) 5(1) -8(1) -5(1)

C(2) 35(2) 19(1) 20(1) -3(1) 0(1) 0(1)

C(3) 30(2) 21(1) 19(1) -2(1) 0(1) 0(1)

C(4) 21(1) 15(1) 18(1) 1(1) 0(1) 1(1)

C(5) 26(2) 21(1) 14(1) 1(1) -1(1) -4(1)

C(6) 26(2) 18(1) 16(1) 0(1) -2(1) -1(1)

C(7) 27(2) 20(1) 17(1) -1(1) -1(1) 4(1)

C(8) 34(2) 18(1) 14(1) 0(1) -3(1) -1(1)

C(9) 39(2) 19(1) 16(1) -3(1) -1(1) 3(1)

C(10) 45(2) 19(1) 21(1) 0(1) 0(1) 0(1)

C(11) 38(2) 24(2) 21(1) 1(1) 3(1) -8(1)

C(12) 28(2) 22(1) 24(1) -1(1) -1(1) 1(1)

C(13) 27(1) 20(1) 18(1) -2(1) -4(1) -1(1)

C(14) 29(2) 21(1) 22(1) -2(1) -1(1) 3(1)

C(15) 27(2) 18(1) 18(1) 1(1) -4(1) 0(1)

179

C(16) 26(1) 16(1) 33(1) 1(1) 6(1) 4(1)

C(17) 28(2) 20(1) 27(1) 2(1) -8(1) 3(1)

C(18) 32(2) 20(1) 27(1) 1(1) -10(1) -2(1)

C(19) 45(2) 21(2) 23(1) 6(1) 6(1) 2(1)

C(20) 26(2) 25(2) 37(1) 9(1) 13(1) 4(1)

C(21) 30(2) 23(2) 33(1) 5(1) 10(1) 5(1)

______

180

Table A.14 Hydrogen coordinates (x 104) and isotropic displacement parameters (Å2 x 10 3) for

3.3b.

______

x y z U(eq)

______

H(1A) 13223 11280 1303 37

H(1B) 12083 12196 912 37

H(2) 9985 11552 1862 30

H(3A) 8746 9887 1793 28

H(3B) 11193 9872 1830 28

H(7) 11388 5224 1183 25

H(9) 9851 3644 1659 30

H(10) 7202 2818 2226 34

H(11) 4220 3689 2570 33

H(12) 3937 5381 2351 30

H(14) 5406 6976 1861 29

H(16A) 8259 12224 831 30

H(16B) 6940 11330 1173 30

H(17) 7115 11140 -116 30

H(18A) 8302 9451 -147 32

H(18B) 6957 9628 570 32

H(19A) 10364 10868 -674 36

H(19B) 10341 11943 -289 36

181

H(20) 13421 11084 11 35

H(21A) 12150 9407 -65 34

H(21B) 13264 9567 703 34

______

182

3.3d: 2(4-methylphenyl)naphtho(2,3-d)oxaphosphole

Table A.15 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (Å2x

103) for 3.3d. U (eq) is defined as one third of the trace of the orthogonalized Uij tensor.

______

x y z U(eq)

______

P(1) 2137(1) 5265(1) -2510(1) 23(1)

P(2) 538(1) 3641(1) 2546(1) 18(1)

O(6) 4345(2) 3970(2) -1954(1) 21(1)

O(26) -1631(1) 5085(3) 2089(1) 16(1)

C(1) 4804(2) 4240(4) 1839(2) 27(1)

C(2) 5171(2) 3839(4) 1149(2) 23(1)

C(3) 4428(2) 4174(4) 291(2) 20(1)

C(4) 4797(2) 3797(4) -422(2) 22(1)

C(5) 4032(2) 4205(4) -1225(2) 21(1)

183

C(7) 3427(2) 4501(4) -2672(2) 22(1)

C(8) 3694(2) 4299(4) -3474(2) 21(1)

C(9) 2892(2) 4939(4) -4254(2) 26(1)

C(10) 3103(2) 4630(4) -5019(2) 25(1)

C(11) 4128(2) 3702(4) -5052(2) 25(1)

C(12) 4330(3) 3321(5) -5899(2) 31(1)

C(13) 3658(2) 5003(4) 1705(2) 26(1)

C(14) 3248(2) 4947(4) 162(2) 22(1)

C(15) 2489(2) 5300(4) -680(2) 21(1)

C(16) 2863(2) 4928(4) -1383(2) 21(1)

C(17) 4743(2) 3418(4) -3499(2) 25(1)

C(18) 4943(2) 3132(4) -4276(2) 25(1)

C(19) 2912(2) 5361(4) 894(2) 24(1)

C(20) -1609(3) 4269(4) 6022(2) 30(1)

C(21) -1392(3) 4329(4) 5169(2) 22(1)

C(22) -332(2) 3627(4) 5093(2) 23(1)

C(23) -107(2) 3687(4) 4317(2) 20(1)

C(24) -936(2) 4453(4) 3591(2) 20(1)

C(25) -699(2) 4461(4) 2774(2) 18(1)

C(27) -1379(2) 4871(4) 1332(2) 17(1)

C(28) -2174(2) 5353(4) 553(2) 17(1)

C(29) -1875(2) 4984(4) -195(2) 19(1)

C(30) -2647(2) 5423(4) -1024(2) 20(1)

184

C(31) -2333(2) 4999(4) -1743(2) 24(1)

C(32) -2219(2) 5098(4) 4447(2) 22(1)

C(33) -2004(2) 5167(4) 3659(2) 20(1)

C(34) -246(2) 4066(4) 1436(2) 18(1)

C(35) -737(2) 4114(4) -109(2) 18(1)

C(36) 48(2) 3684(4) 702(2) 18(1)

C(37) -462(2) 3708(5) -872(2) 22(1)

C(38) -1241(3) 4140(4) -1663(2) 25(1)

______

185

Table A.16 Bond lengths [Å] and angles [°] for 3.3d.

______

P(1)-C(7) 1.716(3) C(11)-C(12) 1.513(4)

P(1)-C(16) 1.789(3) C(13)-C(19) 1.365(4)

P(2)-C(25) 1.723(3) C(14)-C(15) 1.407(4)

P(2)-C(34) 1.787(3) C(14)-C(19) 1.415(4)

O(6)-C(5) 1.373(3) C(15)-C(16) 1.389(4)

O(6)-C(7) 1.374(3) C(17)-C(18) 1.387(4)

O(26)-C(25) 1.372(3) C(20)-C(21) 1.505(4)

O(26)-C(27) 1.376(3) C(21)-C(32) 1.388(4)

C(1)-C(2) 1.368(4) C(21)-C(22) 1.390(4)

C(1)-C(13) 1.410(4) C(22)-C(23) 1.385(4)

C(2)-C(3) 1.421(4) C(23)-C(24) 1.393(4)

C(3)-C(4) 1.403(4) C(24)-C(33) 1.399(4)

C(3)-C(14) 1.450(4) C(24)-C(25) 1.455(4)

C(4)-C(5) 1.369(4) C(27)-C(28) 1.367(4)

C(5)-C(16) 1.417(4) C(27)-C(34) 1.417(4)

C(7)-C(8) 1.458(4) C(28)-C(29) 1.409(4)

C(8)-C(17) 1.405(4) C(29)-C(30) 1.409(4)

C(8)-C(9) 1.405(4) C(29)-C(35) 1.448(3)

C(9)-C(10) 1.377(4) C(30)-C(31) 1.382(4)

C(10)-C(11) 1.401(4) C(31)-C(38) 1.399(4)

C(11)-C(18) 1.390(4) C(32)-C(33) 1.399(4)

186

C(34)-C(36) 1.386(4) C(35)-C(37) 1.424(4)

C(35)-C(36) 1.391(4) C(37)-C(38) 1.365(4)

C(7)-P(1)-C(16) 87.97(13) C(9)-C(10)-C(11) 121.7(3)

C(25)-P(2)-C(34) 88.14(13) C(18)-C(11)-C(10) 117.3(3)

C(5)-O(6)-C(7) 110.9(2) C(18)-C(11)-C(12) 121.5(3)

C(25)-O(26)-C(27) 110.87(19) C(10)-C(11)-C(12) 121.1(3)

C(2)-C(1)-C(13) 119.7(3) C(19)-C(13)-C(1) 120.7(3)

C(1)-C(2)-C(3) 121.9(3) C(15)-C(14)-C(19) 122.2(2)

C(4)-C(3)-C(2) 122.6(2) C(15)-C(14)-C(3) 119.4(3)

C(4)-C(3)-C(14) 119.6(3) C(19)-C(14)-C(3) 118.4(3)

C(2)-C(3)-C(14) 117.8(3) C(16)-C(15)-C(14) 120.7(2)

C(5)-C(4)-C(3) 118.5(2) C(15)-C(16)-C(5) 118.0(3)

C(4)-C(5)-O(6) 122.4(2) C(15)-C(16)-P(1) 131.3(2)

C(4)-C(5)-C(16) 123.8(3) C(5)-C(16)-P(1) 110.7(2)

O(6)-C(5)-C(16) 113.8(2) C(18)-C(17)-C(8) 120.5(3)

O(6)-C(7)-C(8) 114.1(2) C(17)-C(18)-C(11) 121.9(3)

O(6)-C(7)-P(1) 116.6(2) C(13)-C(19)-C(14) 121.5(3)

C(8)-C(7)-P(1) 129.2(2) C(32)-C(21)-C(22) 118.4(2)

C(17)-C(8)-C(9) 117.7(3) C(32)-C(21)-C(20) 121.7(3)

C(17)-C(8)-C(7) 121.4(2) C(22)-C(21)-C(20) 119.9(3)

C(9)-C(8)-C(7) 120.9(3) C(23)-C(22)-C(21) 120.8(2)

C(10)-C(9)-C(8) 120.9(3) C(22)-C(23)-C(24) 120.9(2)

187

C(23)-C(24)-C(33) 118.8(2) C(34)-C(36)-C(35) 120.9(2)

C(23)-C(24)-C(25) 120.2(2) C(38)-C(37)-C(35) 121.1(3)

C(33)-C(24)-C(25) 121.0(2) C(37)-C(38)-C(31) 120.5(3)

O(26)-C(25)-C(24) 114.8(2)

O(26)-C(25)-P(2) 116.39(18)

C(24)-C(25)-P(2) 128.6(2)

C(28)-C(27)-O(26) 122.4(2)

C(28)-C(27)-C(34) 123.5(2)

O(26)-C(27)-C(34) 114.0(2)

C(27)-C(28)-C(29) 118.8(2)

C(28)-C(29)-C(30) 122.3(2)

C(28)-C(29)-C(35) 118.8(2)

C(30)-C(29)-C(35) 118.9(2)

C(31)-C(30)-C(29) 120.5(3)

C(30)-C(31)-C(38) 120.8(3)

C(21)-C(32)-C(33) 121.4(2)

C(24)-C(33)-C(32) 119.7(2)

C(36)-C(34)-C(27) 117.9(2)

C(36)-C(34)-P(2) 131.5(2)

C(27)-C(34)-P(2) 110.5(2)

C(36)-C(35)-C(37) 121.8(2)

C(36)-C(35)-C(29) 120.1(2)

C(37)-C(35)-C(29) 118.1(2)

188

______

Table A.17 Anisotropic displacement parameters (Å2x 103) for 3.3d. The anisotropic displacement factor exponent takes the form: -2 2[ h2 a*2U11 + ... + 2 h k a* b* U12]

______

U11 U22 U33 U23 U13 U12

______

P(1) 16(1) 22(1) 32(1) 3(1) 7(1) 4(1)

P(2) 15(1) 23(1) 18(1) 1(1) 6(1) 3(1)

O(6) 15(1) 19(1) 28(1) 2(1) 7(1) 2(1)

O(26) 14(1) 18(1) 17(1) 0(1) 6(1) 3(1)

C(1) 23(1) 25(2) 30(2) -2(1) 4(1) -2(1)

C(2) 17(1) 16(1) 36(2) 0(1) 9(1) 0(1)

C(3) 14(1) 13(1) 32(2) -1(1) 5(1) -3(1)

C(4) 16(1) 14(1) 35(2) 1(1) 9(1) 1(1)

C(5) 17(1) 14(1) 32(2) -1(1) 10(1) -1(1)

C(7) 20(1) 15(1) 30(2) -1(1) 8(1) 1(1)

C(8) 19(1) 14(1) 30(2) 3(1) 7(1) -3(1)

C(9) 19(1) 22(2) 36(2) 5(1) 8(1) 1(1)

C(10) 20(1) 21(2) 32(2) 7(1) 5(1) -2(1)

C(11) 25(1) 16(1) 35(2) 2(1) 10(1) -4(1)

C(12) 34(2) 29(2) 33(2) 0(1) 15(1) 0(1)

C(13) 27(1) 18(2) 35(2) -5(1) 14(1) -4(1)

C(14) 19(1) 11(1) 35(2) -2(1) 9(1) -1(1)

189

C(15) 12(1) 14(1) 37(2) 2(1) 9(1) 1(1)

C(16) 15(1) 15(1) 33(2) 2(1) 6(1) 1(1)

C(17) 18(1) 19(2) 36(2) 2(1) 9(1) 2(1)

C(18) 22(1) 17(2) 38(2) 1(1) 11(1) 1(1)

C(19) 19(1) 15(1) 38(2) 0(1) 11(1) -1(1)

C(20) 42(2) 27(2) 27(2) -1(1) 18(1) -4(1)

C(21) 33(2) 15(1) 23(1) -3(1) 14(1) -5(1)

C(22) 23(1) 17(1) 27(1) 1(1) 7(1) 1(1)

C(23) 20(1) 20(1) 19(1) -1(1) 4(1) 0(1)

C(24) 19(1) 17(1) 25(1) -4(1) 9(1) -2(1)

C(25) 19(1) 15(1) 20(1) -1(1) 7(1) -1(1)

C(27) 19(1) 15(1) 21(1) -1(1) 10(1) -1(1)

C(28) 12(1) 16(1) 23(1) 0(1) 6(1) 0(1)

C(29) 19(1) 13(1) 25(1) 0(1) 10(1) -3(1)

C(30) 19(1) 19(2) 22(1) 2(1) 6(1) -1(1)

C(31) 25(1) 24(2) 20(1) 3(1) 5(1) -5(1)

C(32) 23(1) 19(2) 26(1) -4(1) 9(1) -2(1)

C(33) 17(1) 18(1) 25(1) -1(1) 6(1) 2(1)

C(34) 14(1) 20(2) 21(1) 2(1) 5(1) -2(1)

C(35) 17(1) 18(2) 20(1) 1(1) 8(1) -4(1)

C(36) 19(1) 12(1) 25(1) 0(1) 12(1) -2(1)

C(37) 22(1) 18(1) 27(1) -3(1) 12(1) -3(1)

C(38) 31(2) 24(2) 23(1) 0(1) 15(1) -4(1)

190

______

Table A.18 Hydrogen coordinates (x 104) and isotropic displacement parameters (Å2 x 10 3) for

3.3d.

______

x y z U(eq)

______

H(1) 5321 4005 2406 32

H(2) 5944 3322 1247 27

H(4) 5562 3271 -350 26

H(9) 2196 5593 -4253 31

H(10) 2539 5057 -5539 30

H(12A) 4897 4213 -5990 47

H(12B) 3564 3411 -6367 47

H(12C) 4660 2094 -5890 47

H(13) 3402 5270 2185 31

H(15) 1712 5798 -768 25

H(17) 5319 3014 -2980 29

H(18) 5658 2531 -4278 30

H(19) 2150 5899 819 28

H(20A) -1537 3012 6232 45

H(20B) -2418 4724 5954 45

H(20C) -1014 5031 6437 45

H(22) 245 3099 5581 27

191

H(23) 622 3200 4278 24

H(28) -2913 5926 516 20

H(30) -3390 6014 -1089 24

H(31) -2865 5296 -2298 28

H(32) -2945 5587 4490 27

H(33) -2581 5696 3171 24

H(36) 795 3121 753 21

H(37) 277 3126 -830 26

H(38) -1040 3854 -2164 30

______

192

4.4: 2,6-diphosphino-1,5-naphthylenediol

Table A.19 Crystal structure determination for 4.15, 4.16a and 4.16c.

4.4 4.5a 4.5c

formula C10 H10 O2 P2 C20 H22 O2 P2 C24 H14 O2 P2

fw 224.12 356.32 396.29

space group P2(1)/c P2(1)/c P2(1)/n

temperature (K) 123 160 100

a (Å) 4.6031(5) 10.5582(7) 3.9088(2)

b (Å) 8.0600(9) 10.0690(7) 19.9940(10)

c (Å) 13.9923(15) 9.5461(7) 11.2543(5)

193

α (deg) 86.660(4) 90.00 90.00

β (deg) 89.391(4) 112.5050(10) 93.829(3)

γ (deg) 74.183(4) 90.00 90.00

V (Å3) 498.62(9) 937.57(11) 877.59(7)

Z 2 2 2

3 densitycalc (g/cm ) 1.493 1.241 1.500 radiation MoK\a (λ = 0.71073 MoK\a (λ = 0.71073 CuK\a (λ = 1.54178

Å) Å) Å) monochromator graphite graphite multilayer mirror

optics detector CCD area detector CCD area detector Bruker SMART 6000 no. of reflns measd hemisphere hemisphere hemisphere

2 θ range (deg) 5.26-50.88 5.82-55.96 8.84-136.52 cryst dimens (mm) 0.33 x 0.10 x 0.06 0.44 x 0.14 x 0.12 0.08 x 0.03 x 0.02 no. of reflns measd 4685 10394 10573 no. of unique reflns 1744 2115 1564 no. of observations 1744 2115 1564 no. of params 147 112 127

R, Rw, Rall 0.0421, 0.1214, 0.0305, 0.0885, 0.0622, 0.1625,

0.0472 0.0349 0.0752

GOF 1.070 1.077 1.046

194

Table A.20 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (Å2x

103) for 4.4. U (eq) is defined as one third of the trace of the orthogonalized Uij tensor.

______

x y z U(eq)

______

P(1) 1468(2) 1204(1) 1564(1) 24(1)

P(2) 9708(2) 8106(1) 3292(1) 23(1)

O(1) 2863(4) 4389(2) 2022(1) 18(1)

O(2) 7599(4) 4871(2) 3034(1) 19(1)

C(1) 3264(5) 2359(3) -244(2) 17(1)

C(2) 2667(5) 2708(3) 726(2) 16(1)

C(3) 3421(5) 4095(3) 1068(2) 14(1)

C(4) 4691(5) 5197(3) 486(2) 14(1)

C(5) 5419(5) 6655(3) 828(2) 17(1)

C(6) 7741(5) 7008(3) 4157(2) 16(1)

C(7) 7003(5) 5544(3) 3917(2) 15(1)

C(8) 5432(5) 4663(3) 4546(2) 14(1)

C(9) 4647(5) 3157(3) 4301(2) 16(1)

C(10) 3106(5) 2371(3) 4926(2) 17(1)

______

195

Table A.21 Bond lengths [Å] and angles [°] for 4.4.

______

P(1)-C(2) 1.826(2) C(4)-C(4)#1 1.422(5)

P(2)-C(6) 1.832(2) C(5)-C(1)#1 1.358(3)

O(1)-C(3) 1.379(3) C(6)-C(7) 1.374(3)

O(2)-C(7) 1.374(3) C(6)-C(10)#2 1.417(3)

C(1)-C(5)#1 1.358(3) C(7)-C(8) 1.413(3)

C(1)-C(2) 1.411(3) C(8)-C(9) 1.418(3)

C(2)-C(3) 1.370(3) C(8)-C(8)#2 1.421(5)

C(3)-C(4) 1.408(3) C(9)-C(10) 1.354(3)

C(4)-C(5) 1.417(3) C(10)-C(6)#2 1.417(3)

C(5)#1-C(1)-C(2) 121.6(2) C(7)-C(6)-C(10)#2 117.9(2)

C(3)-C(2)-C(1) 118.1(2) C(7)-C(6)-P(2) 119.80(18)

C(3)-C(2)-P(1) 119.35(18) C(10)#2-C(6)-P(2) 122.27(18)

C(1)-C(2)-P(1) 121.90(18) O(2)-C(7)-C(6) 122.8(2)

C(2)-C(3)-O(1) 116.9(2) O(2)-C(7)-C(8) 114.7(2)

C(2)-C(3)-C(4) 122.7(2) C(6)-C(7)-C(8) 122.4(2)

O(1)-C(3)-C(4) 120.4(2) C(7)-C(8)-C(9) 122.7(2)

C(3)-C(4)-C(5) 123.0(2) C(7)-C(8)-C(8)#2 118.3(3)

C(3)-C(4)-C(4)#1 118.1(3) C(9)-C(8)-C(8)#2 119.0(3)

C(5)-C(4)-C(4)#1 118.9(3) C(10)-C(9)-C(8) 120.5(2)

C(1)#1-C(5)-C(4) 120.6(2) C(9)-C(10)-C(6)#2 121.9(2)

196

______

Symmetry transformations used to generate equivalent atoms:

#1 -x+1,-y+1,-z #2 -x+1,-y+1,-z+1

197

Table A.22 Anisotropic displacement parameters (Å2x 103) for 4. 4. The anisotropic

displacement factor exponent takes the form: -2 2[ h2 a*2U11 + ... + 2 h k a* b* U12]

______

U11 U22 U33 U23 U13 U12

______

P(1) 32(1) 24(1) 21(1) -2(1) 7(1) -16(1)

P(2) 26(1) 28(1) 18(1) 1(1) 3(1) -15(1)

O(1) 20(1) 30(1) 10(1) -7(1) 3(1) -15(1)

O(2) 19(1) 31(1) 11(1) -8(1) 6(1) -14(1)

C(1) 20(1) 19(1) 16(1) -6(1) -1(1) -11(1)

C(2) 14(1) 18(1) 16(1) -2(1) 1(1) -6(1)

C(3) 13(1) 20(1) 9(1) -4(1) 1(1) -5(1)

C(4) 13(1) 17(1) 12(1) -3(1) 0(1) -5(1)

C(5) 19(1) 20(1) 12(1) -6(1) 1(1) -7(1)

C(6) 15(1) 19(1) 14(1) 0(1) 0(1) -6(1)

C(7) 14(1) 21(1) 9(1) -4(1) 1(1) -4(1)

C(8) 13(1) 18(1) 11(1) -3(1) -1(1) -4(1)

C(9) 18(1) 20(1) 12(1) -6(1) 1(1) -5(1)

C(10) 20(1) 17(1) 17(1) -4(1) -1(1) -6(1)

______

198

Table A.23 Hydrogen coordinates (x 104) and isotropic displacement parameters (Å2 x 10 3) for

4. 4.

______

x y z U(eq)

______

H(1C) 450(50) 350(30) 929(16) 29

H(1D) -960(30) 2260(30) 1916(18) 29

H(2B) 11880(40) 7100(30) 2798(17) 27

H(2C) 10840(50) 8980(30) 3887(16) 27

H(1B) 2732 1410 -494 21

H(5A) 4983 6945 1472 20

H(9A) 5207 2696 3696 19

H(10A) 2579 1373 4743 21

H(1) 3970(70) 4660(40) 2170(20) 17(9)

H(2) 9070(80) 5000(40) 2800(30) 32(9)

______

199

4.5a: 2,7-di-tert-butyl-naphtho[1,2-d:5,6-d’]bisoxaphosphole

Table A.24 Atomic coordinates ( x 10^4) and equivalent isotropic displacement parameters (A^2 x 10^3) for 4.5a. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor.

______

x y z U(eq)

______

P(1) 6578(1) 5869(1) 1119(1) 29(1)

O(2) 8656(1) 4231(1) 2176(1) 27(1)

C(1) 7838(1) 5825(1) 297(1) 27(1)

C(4) 7196(1) 3951(1) 3584(2) 32(1)

C(10) 9974(1) 4627(1) 623(1) 26(1)

C(8) 7930(1) 6548(1) -939(2) 31(1)

C(3) 7485(1) 4662(1) 2346(1) 27(1)

C(5) 6898(2) 2484(2) 3159(2) 44(1)

200

C(6) 8444(2) 4073(2) 5087(2) 47(1)

C(7) 5942(2) 4581(2) 3753(2) 45(1)

C(2) 8839(1) 4902(1) 1020(1) 26(1)

C(9) 8995(1) 6326(1) -1386(1) 30(1)

______

201

Table A.25 Bond lengths [A] and angles [deg] for 4.5a.

______

P(1)-C(3) 1.7050(13)

P(1)-C(1) 1.7853(13)

O(2)-C(2) 1.3694(14)

O(2)-C(3) 1.3771(14)

C(1)-C(2) 1.3779(17)

C(1)-C(8) 1.4212(18)

C(4)-C(3) 1.5089(18)

C(4)-C(7) 1.5310(19)

C(4)-C(5) 1.532(2)

C(4)-C(6) 1.537(2)

C(10)-C(2) 1.4150(17)

C(10)-C(9)#1 1.4245(17)

C(10)-C(10)#1 1.426(2)

C(8)-C(9) 1.3645(18)

C(8)-H(8) 0.9500

C(5)-H(5A) 0.9800

C(5)-H(5B) 0.9800

C(5)-H(5C) 0.9800

C(6)-H(6A) 0.9800

202

C(6)-H(6B) 0.9800

C(6)-H(6C) 0.9800

C(7)-H(7A) 0.9800

C(7)-H(7B) 0.9800

C(7)-H(7C) 0.9800

C(9)-C(10)#1 1.4245(17)

C(9)-H(9) 0.9500

C(3)-P(1)-C(1) 88.15(6)

C(2)-O(2)-C(3) 110.47(10)

C(2)-C(1)-C(8) 118.61(11)

C(2)-C(1)-P(1) 110.72(9)

C(8)-C(1)-P(1) 130.66(10)

C(3)-C(4)-C(7) 109.18(12)

C(3)-C(4)-C(5) 109.38(11)

C(7)-C(4)-C(5) 109.19(12)

C(3)-C(4)-C(6) 109.57(11)

C(7)-C(4)-C(6) 109.63(13)

C(5)-C(4)-C(6) 109.87(13)

C(2)-C(10)-C(9)#1 123.69(11)

C(2)-C(10)-C(10)#1 115.33(14)

C(9)#1-C(10)-C(10)#1 120.98(14)

C(9)-C(8)-C(1) 120.09(12)

C(9)-C(8)-H(8) 120.0

203

C(1)-C(8)-H(8) 120.0

O(2)-C(3)-C(4) 113.75(11)

O(2)-C(3)-P(1) 115.89(9)

C(4)-C(3)-P(1) 130.34(10)

C(4)-C(5)-H(5A) 109.5

C(4)-C(5)-H(5B) 109.5

H(5A)-C(5)-H(5B) 109.5

C(4)-C(5)-H(5C) 109.5

H(5A)-C(5)-H(5C) 109.5

H(5B)-C(5)-H(5C) 109.5

C(4)-C(6)-H(6A) 109.5

C(4)-C(6)-H(6B) 109.5

H(6A)-C(6)-H(6B) 109.5

C(4)-C(6)-H(6C) 109.5

H(6A)-C(6)-H(6C) 109.5

H(6B)-C(6)-H(6C) 109.5

C(4)-C(7)-H(7A) 109.5

C(4)-C(7)-H(7B) 109.5

H(7A)-C(7)-H(7B) 109.5

C(4)-C(7)-H(7C) 109.5

H(7A)-C(7)-H(7C) 109.5

H(7B)-C(7)-H(7C) 109.5

O(2)-C(2)-C(1) 114.76(11)

204

O(2)-C(2)-C(10) 120.97(11)

C(1)-C(2)-C(10) 124.27(11)

C(8)-C(9)-C(10)#1 120.73(12)

C(8)-C(9)-H(9) 119.6

C(10)#1-C(9)-H(9) 119.6

______

Symmetry transformations used to generate equivalent atoms:

#1 -x+2,-y+1,-z

205

Table A.26 Anisotropic displacement parameters (A^2 x 10^3) for 4.5a. The anisotropic displacement factor exponent takes the form:

-2 pi^2 [ h^2 a*^2 U11 + ... + 2 h k a* b* U12 ]

______

U11 U22 U33 U23 U13 U12

______

P(1) 27(1) 31(1) 32(1) -1(1) 15(1) 1(1)

O(2) 27(1) 33(1) 27(1) 3(1) 15(1) 1(1)

C(1) 26(1) 29(1) 28(1) -2(1) 12(1) -1(1)

C(4) 32(1) 38(1) 32(1) 1(1) 20(1) -1(1)

C(10) 26(1) 28(1) 24(1) -1(1) 11(1) -1(1)

C(8) 30(1) 32(1) 33(1) 7(1) 14(1) 6(1)

C(3) 26(1) 30(1) 29(1) -5(1) 14(1) -3(1)

C(5) 56(1) 37(1) 52(1) 3(1) 33(1) -5(1)

C(6) 44(1) 71(1) 29(1) 4(1) 18(1) -6(1)

C(7) 47(1) 50(1) 56(1) 8(1) 38(1) 7(1)

C(2) 28(1) 28(1) 23(1) -1(1) 12(1) -3(1)

C(9) 32(1) 33(1) 27(1) 7(1) 14(1) 2(1)

______

206

Table A.27 Hydrogen coordinates ( x 10^4) and isotropic displacement parameters (A^2 x 10^3) for 4.5a.

______

x y z U(eq)

______

H(8) 7250 7188 -1455 38

H(5A) 6123 2414 2181 66

H(5B) 6671 2030 3940 66

H(5C) 7709 2070 3083 66

H(6A) 9246 3674 4974 70

H(6B) 8255 3610 5889 70

H(6C) 8626 5013 5355 70

H(7A) 6136 5514 4049 68

H(7B) 5732 4104 4533 68

H(7C) 5155 4527 2784 68

H(9) 9048 6811 -2215 36

______

207

4.5c: 2,7-di-phenyl-naphtho[1,2-d:5,6-d’]bisoxaphosphole

Table A.28 Atomic coordinates (x 104) and equivalent isotropic displacement parameters (Å2x

103)for 4.5c. U (eq) is defined as one third of the trace of the orthogonalized Uij tensor.

______

x y z U(eq)

______

P(1) 7711(2) 4914(1) 1420(1) 26(1)

O(1) 4967(5) 4069(1) 2877(2) 26(1)

C(1) 5354(7) 5312(2) 5282(3) 25(1)

C(2) 6905(8) 5845(2) 4670(3) 26(1)

C(3) 7681(7) 5778(2) 3510(3) 26(1)

C(4) 6996(7) 5160(2) 2911(3) 25(1)

C(5) 5519(7) 4644(1) 3521(3) 25(1)

208

C(6) 5983(8) 4143(2) 1738(3) 26(1)

C(7) 5342(7) 3567(2) 971(3) 26(1)

C(8) 3768(8) 2984(2) 1378(3) 28(1)

C(9) 3089(8) 2450(2) 614(3) 31(1)

C(10) 3919(8) 2482(2) -563(3) 31(1)

C(11) 5493(9) 3053(2) -982(3) 31(1)

C(12) 6217(8) 3590(2) -220(3) 28(1)

______

209

Table A.29 Bond lengths [Å] and angles [°] for 4.5c.

______

P(1)-C(6) 1.729(3) C(6)-C(7) 1.452(4)

P(1)-C(4) 1.788(3) C(7)-C(12) 1.406(4)

O(1)-C(5) 1.369(3) C(7)-C(8) 1.410(4)

O(1)-C(6) 1.374(4) C(8)-C(9) 1.384(4)

C(1)-C(5)#1 1.414(4) C(8)-H(8A) 0.9500

C(1)-C(1)#1 1.421(6) C(9)-C(10) 1.386(5)

C(1)-C(2) 1.425(4) C(9)-H(9A) 0.9500

C(2)-C(3) 1.367(4) C(10)-C(11) 1.396(5)

C(2)-H(2A) 0.9500 C(10)-H(10A) 0.9500

C(3)-C(4) 1.425(4) C(11)-C(12) 1.392(5)

C(3)-H(3A) 0.9500 C(11)-H(11A) 0.9500

C(4)-C(5) 1.385(4) C(12)-H(12A) 0.9500

C(5)-C(1)#1 1.414(4)

C(6)-P(1)-C(4) 87.87(14) C(1)-C(2)-H(2A) 119.4

C(5)-O(1)-C(6) 111.0(2) C(2)-C(3)-C(4) 119.3(3)

C(5)#1-C(1)-C(1)#1 115.3(3) C(2)-C(3)-H(3A) 120.4

C(5)#1-C(1)-C(2) 123.5(3) C(4)-C(3)-H(3A) 120.4

C(1)#1-C(1)-C(2) 121.1(3) C(5)-C(4)-C(3) 118.9(3)

C(3)-C(2)-C(1) 121.2(3) C(5)-C(4)-P(1) 110.9(2)

C(3)-C(2)-H(2A) 119.4 C(3)-C(4)-P(1) 130.2(2)

210

O(1)-C(5)-C(4) 114.7(3) C(7)-C(12)-H(12A) 119.7

O(1)-C(5)-C(1)#1 121.1(3)

C(4)-C(5)-C(1)#1 124.2(3)

O(1)-C(6)-C(7) 114.8(3)

O(1)-C(6)-P(1) 115.5(2)

C(7)-C(6)-P(1) 129.7(2)

C(12)-C(7)-C(8) 118.5(3)

C(12)-C(7)-C(6) 119.8(3)

C(8)-C(7)-C(6) 121.7(3)

C(9)-C(8)-C(7) 120.3(3)

C(9)-C(8)-H(8A) 119.8

C(7)-C(8)-H(8A) 119.8

C(8)-C(9)-C(10) 120.8(3)

C(8)-C(9)-H(9A) 119.6

C(10)-C(9)-H(9A) 119.6

C(9)-C(10)-C(11) 119.8(3)

C(9)-C(10)-H(10A) 120.1

C(11)-C(10)-H(10A) 120.1

C(12)-C(11)-C(10) 120.0(3)

C(12)-C(11)-H(11A) 120.0

C(10)-C(11)-H(11A) 120.0

C(11)-C(12)-C(7) 120.7(3)

C(11)-C(12)-H(12A) 119.7

211

______

Symmetry transformations used to generate equivalent atoms:

#1 -x+1,-y+1,-z+1

212

Table A.30 Anisotropic displacement parameters (Å2x 103) for 4.5c. The anisotropic

displacement factor exponent takes the form: -2 2[ h2 a*2U11 + ... + 2 h k a* b* U12 ]

______

U11 U22 U33 U23 U13 U12

______

P(1) 35(1) 20(1) 23(1) 0(1) 8(1) -1(1)

O(1) 35(1) 19(1) 24(1) 0(1) 5(1) 0(1)

C(1) 29(2) 20(2) 26(2) 1(1) 4(1) 3(1)

C(2) 32(2) 16(1) 31(2) 0(1) 4(1) 2(1)

C(3) 31(2) 18(2) 29(2) 3(1) 4(1) -3(1)

C(4) 28(1) 24(2) 21(2) 0(1) 3(1) 4(1)

C(5) 29(2) 16(1) 28(2) -4(1) 2(1) 3(1)

C(6) 32(2) 26(2) 23(2) 3(1) 6(1) 6(1)

C(7) 31(2) 20(2) 28(2) 0(1) 3(1) 5(1)

C(8) 36(2) 25(2) 25(2) 1(1) 5(1) 4(1)

C(9) 35(2) 23(2) 36(2) 2(1) 4(1) 1(1)

C(10) 37(2) 22(2) 32(2) -5(1) -2(1) 4(1)

C(11) 43(2) 28(2) 24(2) -2(1) 7(1) 7(1)

C(12) 36(2) 20(2) 28(2) 2(1) 6(1) 2(1)

______

213

Table A.31 Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x

10 3) for 4.5c.

______

x y z U(eq)

______

H(2A) 7409 6253 5076 32

H(3A) 8667 6140 3106 31

H(8A) 3170 2956 2181 34

H(9A) 2043 2058 900 38

H(10A) 3417 2115 -1083 37

H(11A) 6071 3076 -1788 38

H(12A) 7314 3976 -506 34

______

214

Table A.32 Torsion angles [°] for 4.5c.

______

C(5)#1-C(1)-C(2)-C(3) -179.6(3)

C(1)#1-C(1)-C(2)-C(3) 1.7(5)

C(1)-C(2)-C(3)-C(4) -1.4(4)

C(2)-C(3)-C(4)-C(5) 0.8(4)

C(2)-C(3)-C(4)-P(1) -179.8(2)

C(6)-P(1)-C(4)-C(5) -0.1(2)

C(6)-P(1)-C(4)-C(3) -179.6(3)

C(6)-O(1)-C(5)-C(4) -1.0(3)

C(6)-O(1)-C(5)-C(1)#1 179.6(3)

C(3)-C(4)-C(5)-O(1) -179.8(2)

P(1)-C(4)-C(5)-O(1) 0.7(3)

C(3)-C(4)-C(5)-C(1)#1 -0.4(4)

P(1)-C(4)-C(5)-C(1)#1 -179.9(2)

C(5)-O(1)-C(6)-C(7) -177.2(2)

C(5)-O(1)-C(6)-P(1) 0.9(3)

C(4)-P(1)-C(6)-O(1) -0.5(2)

C(4)-P(1)-C(6)-C(7) 177.4(3)

O(1)-C(6)-C(7)-C(12) 178.8(2)

P(1)-C(6)-C(7)-C(12) 1.0(4)

O(1)-C(6)-C(7)-C(8) 0.5(4)

P(1)-C(6)-C(7)-C(8) -177.3(2)

215

C(12)-C(7)-C(8)-C(9) -0.4(4)

C(6)-C(7)-C(8)-C(9) 177.9(3)

C(7)-C(8)-C(9)-C(10) -0.5(5)

C(8)-C(9)-C(10)-C(11) 0.8(5)

C(9)-C(10)-C(11)-C(12) -0.2(5)

C(10)-C(11)-C(12)-C(7) -0.7(5)

C(8)-C(7)-C(12)-C(11) 1.0(4)

C(6)-C(7)-C(12)-C(11) -177.3(3)

______

Symmetry transformations used to generate equivalent atoms:

#1 -x+1,-y+1,-z+1

216

Appendix B: Selected 31P{1H}, 1H and 13C{1H} NMR Spectra

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

1H-13C COSY: HMQC (Heteronuclear Multiple Quantum Correlation) (600 MHz) for diethyl(3-hydroxy-2-naphthyl)phosphonate (3.12)

233

234

235

236

237

1H-13C COSY: HMQC (Heteronuclear Multiple Quantum Correlation) (600 MHz) for 3-phosphino-2-naphthol (3.13)

238

1H-1H COSY: DQF (Double Quantum Filtered) (600 MHz) for 3-phosphino-2- naphthol (3.13)

239

240

241

242

243

244

245

246

247

1H-1H COSY: DQF (Double Quantum Filtered) (600 MHz) for

2(adamantyl)naphtho(2,3-d)oxaphosphole (3.3b)

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

1H-

281

13C COSY: HMQC (Heteronuclear Multiple Quantum Correlation) (600 MHz) for

2,6-diphosphino-1,5-naphthylenediol (4.4)

282

283

284

285

286

287

288

289

290

291

292

293

294

295

Appendix C. Absorption and Emission Spectra

t 0.08 Bu2-BBOP

304 nm

0.06

Abs. 0.04

0.02

0.00 300 400 Wavelength (nm)

t -6 UV-vis absorption spectrum of Bu2-BBOP (2.28a) (conc. 5.0 x10 M in CH2Cl2)

296

Ad2-BBOP 0.1 306 nm Abs.

300 400 Wavelength (nm)

-6 UV-vis absorption spectrum of Ad2-BBOP (2.28b) (conc. 5.0 x10 M in CH2Cl2)

297

150

tBu -BBOP 372 nm 2

100

50 Emission Intensity (a.u.)

0 300 350 400 450 500 550 Wavelength (nm)

t Fluorescence emission of Bu2-BBOP (2.28a), excited at 300 nm

-6 (conc. 5.0 x10 M in CH2Cl2)

298

160 367 nm 140 Ad2-BBOP 120

100

Emission Intensity (a.u.) 40

0 300 350 400 450 500 550 Wavelength (nm)

Fluorescence emission of Ad2-BBOP (2.28b), excited at 300 nm

-6 (conc. 5.0 x10 M in CH2Cl2)

299

1.0x10-6 M -6 1.0 2.0x10 M 3.0x10-6 M 4.0x10-6 M -6 0.8 5.0x10 M 6.0x10-6 M 7.0x10-6 M -6 0.6 8.0x10 M 333nm 1.0x10-5 M 1.5x10-5 M

Abs. -5 0.4 2.0x10 M 3.0x10-5 M 4.0x10-5 M 5.0x10-5 M 0.2

0.0 300 400 Wavelength(nm)

0.6 at 333 nm

0.4 Abs. 2 0.2 R =0.9989

0.0

0.00000 0.00002 0.00004 0.00006 Concentration (M)

UV-vis absorption spectra of tBu-NOP (3.3a) and Beer’s Law plot

300

1.0x10-6 M 1.0 245nm 2.0x10-6 M 3.0x10-6 M 4.0x10-6 M 0.8 5.0x10-6 M 6.0x10-6 M 7.0x10-6 M 0.6 8.0x10-6 M 1.0x10-5 M -5 Abs. 1.5x10 M 0.4 2.0x10-5 M

0.2

0.0 300 400 Wavelength(nm)

1.0 at 245 nm

0.5 Abs.

2 R =0.99039

0.000000 0.000005 0.000010 0.000015 0.000020 Concentration (M)

UV-vis absorption spectra of tBu-NOP (3.3a) and Beer’s Law plot

301

0.5 1.0 x10-6 M 2.0 x10-6 M 246nm -6 0.4 3.0 x10 M 4.0 x10-6 M 5.0 x10-6 M 6.0 x10-6 M 0.3 7.0 x10-6 M 8.0 x10-6 M Abs. 0.2

333nm 0.1 348nm

0.0 300 400 Wavelength(nm)

at 333 nm 0.4 at 246 nm

0.08

0.3

0.06

0.2 Abs. Abs. 0.04

0.1 2 2 0.02 R = 0.99226 R = 0.99547 0.000002 0.000004 0.000006 0.000008 0.000002 0.000004 0.000006 0.000008 Concentration (M) Concentration (M) at 348 nm

0.06

0.04 Abs.

0.02 2 R = 0.98608 0.000002 0.000004 0.000006 0.000008 Concentration (M) UV-vis absorption spectra of Ad-NOP (3.3b) and Beer’s Law plots

302

0.5 1.0 x10-6 M -6 2.0 x10 M 240nm 3.0 x10-6 M 0.4 4.0 x10-6 M 5.0 x10-6 M

6.0 x10-6 M 0.3 -6 7.0 x10 M 8.0 x10-6 M

Abs. 353nm 0.2 290nm

378nm

0.1

0.0 300 400 Wavelength (nm)

at 290 nm

0.4 at 240 nm 1.0

0.3

Abs. 0.5 Abs.

0.2 2 2 0.0 R = 0.99152 0.1 R = 0.99713 0.000002 0.000004 0.000006 0.000008 0.00000 0.00002 0.00004 Concentration (M) Concentration (M)

at 353 nm at 378 nm 1.5 0.8

0.6 1.0

0.4 Abs. Abs.

0.5 2 0.2 2

0.0 R = 0.99834 0.0 R =0.99877 0.00000 0.00002 0.00004 0.00000 0.00002 0.00004 Concentration (M) Concentration (M)

UV-vis absorption spectra of C6H5-NOP (3.3c) and Beer’s Law plots

303

0.6 1.0 x10-6 M 2.0 x10-6 M -6 3.0 x10 M 4.0 x10-6 M 5.0 x10-6 M 0.4 6.0 x10-6 M

7.0 x10-6 M -6 8.0 x10 M Abs. 294nm 356nm 0.2 378nm

0.0 300 400 Wavelength(nm)

at 294 nm at 356 nm 0.20 0.20

0.15 0.15 Abs. Abs.

0.10 0.10 2 2 0.05 0.05 R = 0.99526 R = 0.98923

0.000002 0.000004 0.000006 0.000008 0.000002 0.000004 0.000006 0.000008 Concentration (M) Concentration (M)

at 378 nm

0.15

0.10 Abs.

0.05 2 R = 0.97479 0.000002 0.000004 0.000006 0.000008 Concentration (M)

UV-vis absorption spectra of 4-MeC6H4-NOP (3.3d) and Beer’s Law plots

304

0.5 1.0 x10-6 M 241nm -6 2.0 x10 M 3.0 x10-6 M 0.4 4.0 x10-6 M 5.0 x10-6 M 6.0 x10-6 M -6 0.3 7.0 x10 M 357nm 8.0 x10-6 M 298nm Abs. 0.2 384nm

0.1

0.0 300 400 Wavelength(nm)

0.2 at 298 nm 0.4 at 241 nm

Abs. 0.1 Abs. 0.2 2 2 R = 0.97783 R = 0.96598

0.000002 0.000004 0.000006 0.000008 0.000002 0.000004 0.000006 0.000008 Concentration (M) Concentration (M)

at 357 nm 0.15 at 384 nm 0.2

0.10 Abs.

0.1 Abs. 2 0.05 2 R = 0.98952 R = 0.98162

0.000002 0.000004 0.000006 0.000008 0.000002 0.000004 0.000006 0.000008 Concentration (M) Concentration (M)

UV-vis absorption spectra of 4-ClC6H4-NOP (3.3e) and Beer’s Law plots

305

-6 0.5 1.0 x10 M 2.0 x10-6 M 3.0 x10-6 M -6 0.4 242nm 4.0 x10 M 5.0 x10-6 M 6.0 x10-6 M -6 7.0 x10 M 0.3 -6 8.0 x10 M 357nm Abs. 0.2 300nm 384nm

0.1

0.0 300 400 Wavelength(nm)

0.4 at 242 nm at 300 nm

0.3 0.15

0.2 0.10 Abs. Abs.

2 2 0.05 0.1 R = 0.99757 R = 0.99789

0.000002 0.000004 0.000006 0.000008 0.000002 0.000004 0.000006 0.000008 Concentration (M) Concentration (M)

at 384 nm at 357 nm 0.20

0.10 0.15 Abs. Abs. 0.10 0.05 2 2 0.05 R = 0.99973 R = 0.99864

0.000002 0.000004 0.000006 0.000008 0.000002 0.000004 0.000006 0.000008 Concentration (M) Concentration (M)

UV-vis absorption spectra of 4-BrC6H4-NOP (3.3f) and Beer’s Law plots

306

-6 0.5 1.0 x10 M 2.0 x10-6 M

3.0 x10-6 M -6 0.4 4.0 x10 M 5.0 x10-6 M 239nm 6.0 x10-6 M 7.0 x10-6 M 0.3 8.0 x10-6 M

Abs. 360nm 0.2 385nm 303nm

0.1

0.0 300 400

0.15 at 239 nm Wavelength(nm) at 303 nm 0.3

0.10 0.2 Abs. Abs.

0.1 0.05 2 2 R = 0.99047 R = 0.97017 0.000002 0.000004 0.000006 0.000008 0.000002 0.000004 0.000006 0.000008 Concentration (M) Concentration (M)

0.20 at 360 nm at 385 nm

0.15 0.15

0.10 0.10 Abs. Abs.

2 0.05 0.05 2 R = 0.9967 R = 0.99676 0.000002 0.000004 0.000006 0.000008 0.000002 0.000004 0.000006 0.000008 Concentration (M) Concentration (M)

UV-vis absorption spectra of 4-MeOC6H4-NOP (3.3g) and Beer’s Law plots

307

tBu-NOP Ad-NOP

C6H5-NOP

4-MeC6H4-NOP

4-ClC6H4-NOP

4-BrC6H4-NOP

4-MeOC6H4-NOP 0.1 Abs.

0.0 300 400 Wavelength(nm)

-6 UV-vis absorption spectra of NOPs (3.3a-g) (conc. 5.0 x10 M in CH2Cl2)

tBu-NOP 1000 Ad-NOP C H -NOP 470nm 6 5

4-MeC6H4-NOP 800 381nm 4-ClC6H4-NOP 464nm 4-BrC6H4-NOP 465nm 4-MeOC H -NOP 600 6 4 465nm 385nm 461nm

400 Emission Intensity(a.u.) 200

0 400 500 600 Wavelength(nm) -6 Fluorescence emission spectra of NOPs (3.3a-g) (conc. 5.0 x10 M in CH2Cl2)

308

tBu-NOP 600 0.06

0.04 400

Abs.

0.02

Emission Intensity(a.u.) 200

0.00 300 350 400 450 500 550

Wavelength(nm) 0

t -6 UV-vis and Fluorescence of Bu-NOP (3.3a) (conc. 5.0 x10 M in CH2Cl2)

Ad-NOP 0.08 800

0.06 600

Abs. 0.04 400

0.02 200 Emission Intensity(a.u.)

0.00 0 300 350 400 450 500 550 Wavelength(nm)

-6 UV-vis and Fluorescence of Ad-NOP (3.3b) (conc. 5.0 x10 M in CH2Cl2)

309

0.15 600 C6H5-NOP

0.10 400

Abs.

0.05 200

Emission Intensity(a.u.)

0.00 0 300 400 500 600 Wavelength(nm)

-6 UV-vis and Fluorescence of C6H5-NOP (3.3c) (conc. 5.0 x10 M in CH2Cl2)

0.20 4-MeC H -NOP 6 4 800

0.15 600

0.10

Abs. 400

0.05

200 Emission Intensity(a.u.)

0.00 0 300 400 500 600 700 Wavelength(nm)

-6 UV-vis and Fluorescence of 4-MeC6H4-NOP (3.3d) (conc. 5.0 x10 M in CH2Cl2)

310

0.18 800 4-ClC6H4-NOP 0.16

0.14 600 0.12

0.10 400

Abs. 0.08

0.06 200

0.04 Emission Intensity(a.u.)

0.02

0.00 0 300 400 500 600 Wavelength(nm)

-6 UV-vis and Fluorescence of 4-ClC6H4-NOP (3.3e) (conc. 5.0 x10 M in CH2Cl2)

0.18 4-BrC H -NOP 6 4 0.16 600 0.14

0.12

0.10 400

Abs. 0.08

0.06 200

0.04 Emission Intensity(a.u.) 0.02

0.00 0 300 400 500 600 700 Wavelength(nm)

-6 UV-vis and Fluorescence of 4-BrC6H4-NOP (3.3f) (conc. 5.0 x10 M in CH2Cl2)

311

0.16 1000 4-MeOC6H4-NOP 0.14 800 0.12

0.10 600

0.08 Abs. 400 0.06

0.04 200 Emission Intensity(a.u.) 0.02

0.00 0 300 400 500 600 700 Wavelength(nm)

-6 UV-vis and Fluorescence of 4-MeOC6H4-NOP (3.3g) (conc. 5.0 x10 M in CH2Cl2)

312

0.5 -6 273 nm 1.0 X 10 M 2.0 X 10-6 M 3.0 X 10-6 M 0.4 4.0 X 10-6 M 5.0 X 10-6 M 6.0 X 10-6 M 0.3 7.0 X 10-6 M 8.0 X 10-6 M

Abs. 316 nm 0.2

0.1

0.0 300 400 Wavelength (nm)

0.20 at 316 nm at 273 nm

0.4 0.15

0.10 Abs. Abs. 0.2

R2= 0.99422 0.05 R2= 0.99056

0.000002 0.000004 0.000006 0.000008 0.000002 0.000004 0.000006 0.000008 Concentration (M) Concentration (M)

t UV-vis absorption spectra of Bu2-NBOP (4.5a) and Beer’s Law plots

313

0.5 274 nm 1.0 X 10-6 M 2.0 X 10-6 M 3.0 X 10-6 M 0.4 4.0 X 10-6 M 5.0 X 10-6 M 6.0 X 10-6 M 0.3 7.0 X 10-6 M 8.0 X 10-6 M

Abs. 318 nm 0.2

0.1

0.0 300 400 Wavelength(nm)

0.5 0.20 at 274 nm at 318 nm

0.4 0.15

0.3 0.10 Abs. 0.2 Abs.

0.05 0.1 2 R2= 0.98857 R = 0.98696

0.0 0.00

0.000000 0.000002 0.000004 0.000006 0.000008 0.000000 0.000002 0.000004 0.000006 0.000008 Concentration (M) Concentration (M)

UV-vis absorption spectra of Ad2-NBOP (4.5b) and Beer’s Law plots

314

1.0 X 10-6 M 2.0 X 10-6 M 3.0 X 10-6 M 0.4 4.0 X 10-6 M 387 nm 5.0 X 10-6 M 372 nm 6.0 X 10-6 M 232 nm 268 nm -6 0.3 7.0 X 10 M 8.0 X 10-6 M 5.0 X 10-7 M

Abs. 0.2

0.1

0.0 300 400 Wavelength (nm)

at 372 nm at 387 nm

0.3 0.3

0.2 0.2 Abs. Abs.

0.1 0.1

R2= 0.9993 R2= 0.99913

0.000000 0.000002 0.000004 0.000006 0.000008 0.000000 0.000002 0.000004 0.000006 0.000008 Cpncentration (M) Concentration (M)

UV-vis absorption spectra of Ph2-NBOP (4.5c) and Beer’s Law plots

315

0.35 Abs Emission excited at 316 800 273 nm 0.30 368 nm

0.25 600

351 nm 0.20 386 nm 400 Abs. 0.15 316 nm

0.10 200 Intensity(a.u.)Emmision

0.05

0.00 0 300 400 Wavelength (nm)

t -6 UV-vis and fluorescence of Bu2-NBOP (4.5a) (conc. 5.0 x10 M in CH2Cl2)

316

Abs. 1000 Emission excited at 318 nm 0.30 274 nm 369 nm 0.25 800

0.20 352 nm 600 387 nm 0.15 Abs. 318 nm 400

0.10 Emmision IntensityEmmision (a.u.)

200 0.05

0.00 0 300 400 500 Wavelength (nm)

UV-vis and fluorescence spectra of Ab2-NBOP (4.5b)

-6 (conc. 5.0 x10 M in CH2Cl2)

317

0.30 Abs Emission excited at 387 0.25 387 nm 422 nm 372 nm 1000 0.20 conc. 5.0 x 10-7 M 0.15 Abs. 500 0.10 Emmision Intensity(a.u.)Emmision

0.05

0.00 0 400 500 Wavelength (nm)

UV-vis and Fluorescence spectra of Ph2-NBOP (4.5c)

-6 -7 (conc. 5.0 x10 M for UV and conc. 5.0 x10 M for Fluorescence in CH2Cl2)

318

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